ON THE ANGUILLULID^. 139 



ende abgerundet, Schwanzende beim Mannchen stark verdiinnt, weniger bei dem Weib- 

 cben, leicht eingebogen." 



" Weibchen 3 Mm. lang, 1 Mm. breit. 



" Mannchen 6-6 Mm. lang. 



" Oesophagus =em Sechstel der Korperlange." 



I have retained this species provisionally in the genus Oncholaimus, where it was 

 placed by Eberth, though the representation he has given of this animal seems to indi- 

 cate that it possesses a form of pharynx different, not only from that characteristic of the 

 genus Oncholaimus, but also from that possessed by any other type that I have yet 

 examined. 



10. O. Echini, Leydig. 



Miiller's Archiv, 1854, p. 291.— Diesing, Sitzungsb. der Kais. Akad. Bd. xlii. (1861) p. 626.— Eberth, 

 Untersuch. iiber Nemat. p. 25. 



" Corpus utrinque attenuatum. Os dentibus pluribus instructum. Ovipara. 

 Longit. 4'"." 



" Sab. Echinus esculentus, in intestinis {Leydig)." 



Probably swallowed accidentally ; and it seems doubtful whether it really belongs to 

 this genus. 



11. O. RiVALis, Leydig. 



Miiller's Archiv, 1854, p. 291, tab.xi. 89.— Diesing, Sitzungsb. der Kais. Akad. Bd. xlii. (1861) p. 626. 

 — Eberth, Untersuch. iiber Nemat. p. 25. 



" Os dentibus duobus lateralibus et tertio intermedio denticulate instructum. Vivi- 

 para. Longit " 



"Sab. Sub saxis Meni frequenter {Leydig).'" 



If this really belongs to the genus Oncholaimus, it is the only freshwater species yet 

 discovered. 



16. ENCHELIDIUM, Ehrenberg. 



" Body often 3-6 nam. long, straight or slightly curved. Head blunt, rounded off or 

 truncate. Posterior extremity pointed, provided with a perforated sucker. Mouth 

 plain, or with four small punctiform papillse. 



" Skin consisting of two or three layers, having, especially on fore part of body, 

 several hairs implanted in its substance ; larger cu'rhi around the mouth. Behind the 

 pharynx there opens on the ventral surface either a small gland or a tube reaching to 

 commencement of intestine. 



•' An agglomeration of small cells in the place of tail-glands. 



" Lateral lines simple, narrow, cellular cords. 



" Organs of Digestion. — No pharynx. Qilsophagus cylindrical, widening posteriorly ; 

 the external sheath finely granular, or transversely striped. Anus at the base of taU. 



" Organs of Generation. — Two spicules, or a larger and a smaller pair, the latter being 

 rather posterior. 



t2 



