ON THE ANGUILLULIDÆ. 139 
ende abgerundet, Schwanzende beim Männchen stark verdünnt, weniger bei dem Weib- 
chen, leicht eingebogen." 
« Weibchen 3 Mm. lang, 1 Mm. breit. 
« Männchen 5-6 Mm. lang. 
' « Oesophagus=ein Sechstel der Körperlänge.” 
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. ©. Ecusi, Leydig. 
Müllers Archiv, 1854, p. 291.—Diesing, Sitzungsb. der Kais. Akad. Bd. xlii. (1861) p. 626.— Eberth, 
Untersuch. über Nemat. p. 25. 
“Corpus utrinque attenuatum. Os dentibus pluribus instructum, Ovipara. 
Longit. 4." 
* Hab. Echinus esculentus, in intestinis (Leydig).” 
Probably swallowed accidentally ; and it seems doubtful whether it really belongs to 
this genus. 
11. ©. rivauis, Leydig. 
Müller's Archiv, 1854, p. 291, tab. xi. 89.— Diesing, Sitzungsb. der Kais. Akad. Bd. xlii. (1861) p. 626. 
—Eberth, Untersuch. über Nemat. p. 25. 
* Os dentibus duobus lateralibus et tertio intermedio denticulato instructum. Vivi- 
peu Longit. ...... te 
* Hab. Sub saxis Meni frequenter (Leydig).” 
If this really belongs to the genus Oucholaimus, it is the only freshwater species yet 
discovered. 
16. ENCHELIDIUM, Ehrenberg, 
* Body often 3-6 mm. 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 papillæ. 
" Skin consisting of two or three layers, having, especially on fore part of body, 
several hairs implanted in its substance; larger cirrhi 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. (Esophagus cylindrical, widening posteriorly ; 
the external sheath finely granular, or transversely striped. Anus at the base of tail. 
" Organs of Generation.—Iwo spicules, or a larger and a smaller pair, the latter being 
rather posterior. 
T 2 
