90 MR. H. CHARLTON BASTIAN’S MONOGRAPH 
Tt Ceca. 
6. Oncholaimus. 7. Dorylaimus. 8. Odontobius. 9. Diplogaster, 
** Anoplostomata. Os edentatum. 
10. Dicelis. 11. Anguillula. 12. Angiostomum. 13. Leptodera. 14. Isacis, 
Genera inquirenda. 
15. Phacelura. 16. Potamonema. 17. Nema. 
` More extended observation has convinced not only myself, but also Dr. Eberth, that 
this character, derived from the presence or absence of cirrhi, selected by Diesing as a 
family distinetion, is altogether too inconsistent and variable. Several of the genera 
placed by Diesing in that family the members of which are supposed by him to haye 
no cirrhi contain species which are abundantly furnished with these appendages, such 
as Enoplus, Oncholaimus, and Odontobius ; and, moreover, their presence or absence is 
not always a character of sufficient importance to be employed even as a generic dis. 
tinction. Five of these genera too, Dicelis, Angiostomum, Leptodera, Isacis, and Pha- 
celura, are composed of species which are not free Nematodes at all, but parasitic forms 
infesting various kinds of insects, mollusks, myriapods, &c., concerning which I have 
already expressed my unwillingness to admit their identity with the free Nematoids till 
such a relation shall be fully established by a more accurate and precise knowledge of 
their anatomy than we at present possess. 
Dr. Eberth also rejects this arrangement of the free Nematoids by Diesing as unsatis- 
factory, and offers in its place a readjustment of his own. He divides them into two 
prineipal families, but is doubtful and uncertain about some genera, such as Dorylaimus, 
Diplogaster, Phanoglene, and Pontonema. His main divisions are as follows :— 
l. Anguillule. 
a. Nematodes with an unarmed mouth, with a cylindrical œsophagus, and well-marked stomach; 
without tail-glands or ocelli ; partly free and partly parasitic. 
b. Nematodes with an unarmed mouth and simple &sophagus, without stomach and without 
tail-glands. 
Urolabes. Nematodes without well-defined stomach, partly with and partly without cirrhi around 
the mouth; with or without ocelli, but provided with well-defined tail-glands. Habitat, fresh 
and salt water. 
a. Apharyngea. 
Amblyura, Phanoglene. Enchelidium. 
6. Pharyngea, 
* 
te 
* Cæca. Oncholaimus. Odontobius. 
** Ocellata, Enoplus. 
