Die Borstenwürmer (Annelida Chaetopoda) nach systematischen und anatomischen Untersuchungen dargestellt / von Ernst Ehlers.

Abstract

The work on the setigerous Annelids by Ehlers, of which the first part now lies before us, will henceforth be no less indispensable to students of this group than the well-known treatise of Audouin and Milne-Edwards. Like that monograph, though chiefly devoted to the fauna of a limited region, it enters also into many particulars touching the higher Annelida in general, their structure, habits, and systematic arrangement. After a short introduction on the distinctive features of the several animal forms referred to the type Vermes of modern naturalists, it proceeds to treat in a separate chapter of the characters common to the setigerous subclass, under the heads of (1) general organization, (2) conditions of life, and (3) classification. Then follows a general account of the first order, Nereidea, here divided into eleven families. More detailed notices of seven of these occupy the second and principal moiety of the work. Twenty-five new species of Nereidea, from Quarnero and its neighbourhood, are described with great minuteness, as is like-wise the Phyllodoce lamelligera of Johnston, found by Ehlers in the same district. Six of these species belong to new genera, and one to a new family-Chrysopetalea. Five new genera are also founded for the reception of species previously known. A few obscure or doubtful species not new to science are briefly noticed. To the detailed account of each new species afforded by the text a more concise definition, in small type, is prefixed. Similar definitions, but without descriptions, of the genera to which these species severally belong, and of various critical species referable to other genera, are given. All the families are defined, and, in addition, most of them are reviewed at considerable length, their genera enumerated, or even further illustrated with the aid of tabular views in which their essential characters are curtly compared. This especially applies to the families Hesionea and Syllidea, which last includes the author's five new critical genera. The plates appended to this part refer chiefly to details of external anatomy; but internal structure is not neglected. Four families of Nereidea, besides the other orders of Choetopoda, remain for treatment in the succeeding divisions of the work. .Podarke (ibid.). Body compact, most of its segments marked with transverse bands; prestomium with five tactile cirri; first three segments without setigerous parapodia, but with tactile cirri; parapodium of each succeeding segment large, single, or with a second, superior, tubercular process; setae (of the parapodium proper) compound, with pointed, knife-shaped appendages, those of the upper process simple, capillary; dorsal cirrus with basal joint, otherwise undivided; ventral cirrus always much shorter; posterior segment with lateral appendages and anal cirri or papilla; proboscis destitute of papillae. . Periboea (ibid.). Prestomium with two filiform tactile cirri and a pair of longer and thicker tri-articulate palpi arising from its under surface; peristomium with three, second and third segments each with two pairs of cirri; parapodium very large, undivided, with pointed lips; setoe compound ; dorsal cirrus very long, ventral cirrus shorter; posterior segment with anal cirri; anterior extremity of proboscis with a circlet of filiform papillae. Proceroea, Distinguished from other Syllidea without palpi by the long cirri which arise from its first three segments and from these only. Eurysyllis may be known by the complete absence of these long cirri. . Ehlers (op. cit. pp. 12-14), on the other hand, suggests affinities between Peripatus and the Tardigrada. EHLERS, on the other hand, divides Vermes into these eight "classes":- I. Cestoda, Rud. II. Acanthocephala, Rud. Trematoda, Rud. Turbellaria, Ehrbrg.s.str. V. Nemertina,M. Schultze. VI. Nematoda, Rud. VII. Gephvrea, Qtrfgs. VIII. Annelida, Sav. EHLERS distinguishes the following families of Nereidea:- Amphinomea, Sav. Chrysopetalea. Aphroditea, Sav. s. str. Phyllodocea, Gr. s. str. Alciopea. Hesionea, Gr. Syllidea; Gr. Eunicea, Gr. Lycoridea, Gr. Nephthydea, Gr. Glyecrea, Gr. The new family Chrysopetalea is thus characterized:- Chrysopetalea, Elders. Prestomium conspicuously furnished with eyes and tactile appendages; the peristomium with tactile cirri; the body-somites with similar appendages; palpi on the back of each segment. Besides his new genus, Chrysopetalum, Ehlers would refer to this family Paleanotus and Bhawania of Schmarda. Here, also, he places (with a query) Palmyra (Sav.), which, with Kinberg, he excludes from the Aphroditea. Kinberg's division of the Aphroditea into six subfamilies (Aphroditacea, Iphionea, Polynoina, Acoetea, Sigalionina, and Pholoidea) he seems disposed to accept. From Phyllodocea he removes Alciope, to constitute a distinct family including this genus and Liocape of Costa. Ehlers, on the other hand, takes up the entire group of Syllidae; and his investigations derive additional importance from the circumstance that they are quite independent of those of Claparede. All the genera and species known to the author, from his own observations or the writings of others, are cited, with bibliographical references, and their systematic position is, at the same time, displayed. New species are described, and new genera established, while a critical survey is taken of the whole family. The work of Ehlers, being chiefly devoted to new species, takes less heed of those already known to naturalists. Inciden-tal notices of many of these will be found, however, scattered through its pages. Besides his detailed account of the Syllidoe, the author gives a complete list, accompanied with bibliographical references, of the species of Euphrosyne and Syllis. Those of Euphrosyne, ten in number, are further discriminated by means of short definitions. The following Polychoeeta are made the subject of comment by Claparede:- Polyophthalmus pictus (De Q.) ; Aphlebina (De Q), two species; Dasybranchus caducus (Gr.); Syllis gracilis (Gr.); Syllides pulliger (=Syllis pulligera, Krohn); Sphoerosyllis hystrix (Clap.); S. pusilla (=Exogons, sp., Duj.); Odontosyllis fulgurans ( = Syllis, sp., Aud, Edw.) ; Lumbriconereis unicornis (Gr.); Eunice harassii (A., E.); Micronereis tariegata (Clap.). The first of these species is the Nais picta of Dujardin, whose account of this Annelid, hitherto the only one accessible to the student, contained several errors. Grube refers it to Dero ; Quatrefages, with whom Claparede is disposed to agree, to Polyophthalmus. Perhaps it should form a new genus. Claparede gives a long description of its structure, showing it to be an undoubted Polychaetan, but, like Thysonoplea luctuosa (Schmidt) and Drilidium (Fr. Muller), tending to unite the characters of the two groups of setigerous worms. Ehlers gives lengthened descriptions of the following (all from Quarnero):- AMPHINOMEA.-Euphrosyne racemosa. CHRYSOPETALRA.-Chrysopetalum fragile. APHRODITEA.-Polynoe spinifera; P. pellucida; Sigalion limicola. PHYLLODOCEA.-Phyllodoce vittata; P. lugens; Eulalia virens; E. volucris; E. obtecta; Eteone pterophora. HESIONEA.-Orseis pulla; Podarke albocincta; P. viridetescens; P. agilis; Periboea longicirrata. SYLLIDEA.-Syllis fiumensis; S. krohnii; S. pellucida; S. sexoculata; S. scabra; S. (248-50)?; Sphaerosyllis claparedii; Proceraea picta; Eurysyllis tuberculata. Chrysopetalum. Characters of the family. Body short, nearly as broad, with few segments; parapodium with one setigerous tuft; prestomium with three tactile appendages and two palpi; peristomium with four tactile cirri on either side. In addition to his own C. fragile, Ehlers thinks Palmyra debilis (Grube) may also belong to this genus. Orseis (Hesionea). Body compact, with very distinct segments; prestomium with five tactile cirri; peristomium with two tactile cirri on either side; parapodium unbranched, its dorsal and ventral cirri united; posterior segment with lateral processes and terminal anal cirri; anterior extremity of everted proboscis with a circlet of pointed papillae. Five other critical genera of Syllidea are established by Ehlers, viz:- Procome. Palpi; peristomium without setae, but with more than two pain of tactile cirri. Sp. Syllis polycera (Schmarda). Exotokas, As Procome, but peristontium with only a single pair of tactile cirri; three antennae. Includes Erogone kefersteinii (Clap.) and E. gemmifera (Pag.). The closely allied Microsyllis has but two antennae. Exogons proper differs from both these genera in possessing ventral cirri. Isosyllis. Palpi; peristomium with setae; three antenna. Includes Syllis inaculosa (M.-Edw.) and S. armoricana (Clap.) Oophylax. As last, but with four antennae. Includes Exogone oerstedii (Koll.) and E. cirrata (Koll.). Euerastes. No palpi; long cirri from all the segments; cirri thick, club-shaped. Sp. Myrianida clavigera (Schmarda).