116 OPHIODROMUS. 



De Quatrefages (1865) again made a family, the Hesionea, for their reception, 

 holding that they and the Syllids were analogous groups, allied to each other, yet pre- 

 senting special modifications of the digestive system and other parts. He grouped them 

 according to the condition of the feet, the length of the body, and the number of tentacles 

 and tentacular cirri. His first genus Myriana contains a doubtful form, possibly from 

 its length, Myrianida. He included several members of the family amongst his Syllids, 

 instituting, for instance, a new genus for Gastalia fusea — of which he made two species, 

 viz. Kefersteinia cirrata and K. Glaparedii. 



Claparede (1868) criticised De Quatrefages for lamenting the absence of correct 

 structural details of the group, for he had overlooked Keferstein's description of Psamathe, 

 and yet removed the genus Kefersteinia to the Syllidse without adequate reason. 



The Hesionidse formed one of the families of the Syllidiformia vera of Levinsen l 

 along with the Nereidas, Syllidse, Nerillida3, and Sphserodoridse, and in Benham's 2 more 

 recent classification, which has certain features in common with the foregoing, it is 

 further linked to the Aphroditiclae (a relationship difficult to appreciate) under the sub- 

 order JSTereidiformia. 



Gravier (1900) arranged this family like his predecessors, viz., according to the 

 uniramous or biramous condition of the feet, the number of tentacular cirri, the condition 

 of the proboscis, the tentacles, and the structure of the feet. 



Genus XXXIX. — Ophiodbomus, Sars, 1861. 

 Oxydromus, Grube, 1853. 



Head trapezoidal with two pairs of eyes; tentacles filiform; palpi thick, Particu- 

 late; six long, non-articulate tentacular cirri on each side. Body of moderate length. 

 Proboscis short, sub-globose or shortly cylindrical; unarmed. Feet bifid, sub-equal, 

 cylindrical, each lingule elongate, almost cirriform; dorsal cirrus long, non- articulate ; 

 ventral cirrus shorter, arising from tip; dorsal bristles capillary, inferior compound- 

 falcate. Body-wall as in Fig. 46. 



Goodrich (1901) observed that the genital funnel in Ophiodromus is smaller than in 

 Hesione, but is more intimately connected with the segmental organ, so that the internal 

 opening " can scarcely be said to exist as such." 3 



In the genera Leocrates (Tyrrhena), Ojohiodromus, and Irma, a gradually closer and 

 closer union is established between the funnel and the segmental trumpet. In Irma, 

 where the genital funnel is well developed, it is so completely fused with the segmental 

 trumpet that the two organs can be distinguished only by their histological structure. 

 The segmental organ thus acquires a large trumpet-shaped opening into the ccelom and 

 acts both as a genital and an excretory duct (Goodrich). 



1 c Yidenskab. Meddel. Nat. Foren. Kjobenh./ 1883, p. 180. 

 3 ' Camb. Nat. Hist./ ii, pp. 258 and 308. 

 3 f Quart. J. Micr. Sc./ n. s., vol. xliii, p. 714. 



