432 ASCOGLOSSA — NUDIBRANCHIATA chap. 



the Cladohepatic Nudibranchs, while the Pleurobranchidae form 



a somewhat simihir link between the Holohepatic Nudibranchs 



and the other Tectibranchiata. 



Fam. 1. Oxynoeidae} — Animal long, tentacles auriform, 



epipodia large, simple, or wing-like, a ctenidium and branchial 



chamber on right side, shell small, thin, 

 slightly spiral, not covering much of 

 the body. Genera: Oxynoe Q = Loplio- 

 cercus)^ Lohiger. 



Fam. 2. Hermaeidae. — Body de- 

 pressed, cerata in several rows, no 

 branchiae, no shell. Genera : Hermaea^ 

 Phyllohranchus, Stilige7\ Alderia. 



Fig. 288.— Raduia of one of F A^sL S. Ulysiidae. — Body depressed, 



AscogiossajEiysia viridis ^.q^^ rather elevated, tentacles auriform, 



Mont. X iO). ' ' 



sides of body dilated into two large 

 wings, which enclose branches of the liver and sometimes fold 

 over the dorsal surface, no branchiae, no shell. Genera : Ulysia, 

 Thridachia^ Placohranchus. 



Fam. 4. Limapo7itiidae. — Body slug-like, liver scarcely 

 ramified, no branchiae, shell, or appendages. Genera: Lima- 

 pontia^ Actaeonia, Cenia. 



Sub-order III. Nudibranchiata. — Shell absent in the adult, 

 no ctenidium proper, or osphradium, cerata dorsal or dorso-lateral, 

 nervous system concentrated, kidney not compact, ramified, penis 

 retractile, jaws and raduia usually present. 



Section I. Cladohepatica. — Cerata usually latero-dorsal, 

 elongated, or arborescent, buccal mass strong, jaws present, liver 

 generally ramified, rami generally entering the cerata. 



Fam. 1. Aeolidiidae. — Body slug-like, head with tentacles 

 and rhinophores, dorsal area with rows of cerata, which usually 

 contain sting-cells, raduia variable. Genera : Aeolis^ Cratena^ 

 Tergipes^ Coryphella^ Favorinus^ Faeelina., Flahellina^ Fiona^ 

 Glaucus^ Janus^ Hero^ with many sub-genera. 



Fam. 2. Tethymelibidae. — Body slug-like, large, cerata very 

 large, no sting-cells, head large, cowl-shaped, no tentacles, rhino- 

 phores much foliated, no raduia. Genera : Tethys^ 3Ielibe. The 

 cerata of Tethys, which are capable of independent movement 



1 This family has also been classified with the Bulloidea and with the 

 Aplysioidea. 



