248 APPENDIX TO NEMATODA 



and an unpaired vesicle at the head-end. The tail-end bears 

 a pair of vesicles. Mouth in a shallow depression on the 

 anterior surface of the head -vesicle. Anus in front of the 

 posterior pair of vesicles. Body-wall apparently without 

 musculature. Male unknown. Body of female contains a 

 utenis and a thin-walled gut. The body-cavity is filled with 

 embryos, which extend even into the vesicles, by the rupture 

 of which they probably escape. Vulva apparently absent. 



Hab. Connective tissue of a Shark (Lamna), between the 

 hyomandibular arch and the skull. 

 Genotype : P. lamnae Steiner, 1921. 



Steiner, 1921, Centralbl.f. Bakt., (1), Ixxxvi, 590. 



22. Piguris Schlotthauber, 1860. 



The description of P. reticulata Schotthauber, 1860, from 

 the colon of the horse, does not enable its systematic position 

 to be determined. 



Schlotthauber, 1860, Versamml. deutsch. Naturf. u. Aerzt., 

 xxxi, 126. 



23. Pontonema Leidy, 1855. 



" Body capillary, narrowing towards the extremities. 

 Head continuous with the body, truncated, or obtuse and 

 surmounted with angular papillae, cirrated. Eyes none. 

 Tail obtuse. Generative aperture ventral, near the middle of 

 the body. Oesophagus long, cylindroclavate ; gizzard none, 

 intestine straight, capacious; anus ventral and posterior." 



Hab. Marine. 



Genotype : P. vacillatum Leidy, 1855. 



Leidy, 1855, Journ. Acad. Nat. Sci. Philadelphia, (2) iii, 

 144; 1856, Proc. Acad. Nat. Sci. Philadelphia, viii, 49. 



24. Potamonema Leidy, 1856. 



" Body filiform, narrowing towards the extremities. Head 

 continuous with the body, slightly dilated, obtuse. Mouth 

 large, infmidibuliform, una,rmed ; oesophagus narrow, flexu- 

 ous, membranous, gradually expanding into a capacious, 

 straight, cylindrical intestine; anus none (?) or exceedingly 

 indistinct. Caudal extremity obtuse. Generative aperture 

 of the female near the middle of the body." 



Hab. Fresh water. 



Genotype : P. nitidum Leidy, 1856. 



Leidy, 1856, Proc. Acad. Nat. Sci. Philadelphia, viii, 49. 



25. Prothelmins v. Linstow, 1888. 



An elongate form, of large size for a free-living Nematode, 

 rounded at both extremities, the posterior end being the thicker. 



