Ou the Striicture aud Affiuities of Mnestra paiasites Krohn etc. 57 



Sub-family 1 . P t e r u e mi cT a e. 



Cladonemidae with unbranched tentacles armcd witb cnidophors along 

 the abaxial side. Kadial canals 4, simple or forked. 



Group a. Cnidophors stalked and knob-shaped. Radial canals simple. 

 Oral tentacles absent. 



I. "Scheitclhöhle'' present as a brood pouch. 

 Pteronema Haeckel. 



Tentacles 4; cnidacts on exumbrella absent. 

 II. "öcheitelhöhle" absent as a brood pouch. 

 Zanclea Gegenbaur. 



Tentacles 4; cnidacts on exumbrella 4. 

 Mnestra Krohn. 



Tentacles 4 — ü; cnidacts ou exumbrella 4; sessile on 

 Phìjllirlio'è. 

 Gemmaria Me Crady. 



Tentacles 2; cnidacts on exumbrella absent, but 4 nenia- 

 tocyst tubes lie beneath the surface of the exum- 

 brella. 

 Group ,3. Cnidophors filiform. Radial canals forked. Oral tentacles 

 present. 



Ctenaria Haeckel. 



Tentacles 2; cnidacts on exumbrella 8; tentacular pouches 

 2; "Scheitelhöhle" present. 



Sub-famih' 2. Deudronemidae. 



Cladonemidae with branched tentacles; the branches turned towards the 

 mouth (axial) end in suckers, those turned away from the luouth (abaxial) end 

 in batteries of nematocysts. 



Group 7. Axial and abaxial branches of tentacles are simple and undi- 

 vided. Radial canals simple. Oral tentacles absent. 

 Eleuthei'ia Quatrefages. 



Scheitelhöhle, of peculiar structure, present; cnidacts 

 absent. 

 Group ß. Abaxial branches of tentacles brauch dichotomously. Radial 

 canals forked (usually). Oral tentacles present. 

 Cladonema Dujardin. 



Oral tentacles 4, simple; Scheitelhöhle absent; Cnidacts 

 absent. 

 Dendroncma Haeckel. 



Oral tentacles in 4 bundles, branched; Scheitelhöhle 

 present; Cnidacts absent. 

 After drawing up this scheme for the Classification of the Cladonemidae, 

 I was pleased to find that it agrees with the short sketch of a natural system 

 prepared by Vanhöffen and foUowed by Delage & Hkrouard in so far as 

 the division of the genera into Pteronemidae and Dendronemidae is concerned, 

 but I cannot agree with the former in regarding the Cladonemidae as a subgroup 



