With caudal fork; 
I. 
Without caudal fork ; 
2. 
With bristles ; 
3- 
Without bristles; 
4- 
Head with tentacles, hinder end slightly lobed; 
Gossea. 
Head without tentacles, hinder end rounded ; 
DasydyHs. 
Caudal fork simple ; 
Chcetonotus. 
Caudal fork dichotomous; 
ChcBtura. 
Skin smooth ; 
Ichthydium. 
Skin with scales or hooks ; 
Lepidoderma. 
Ichthydium podura (O. F. Muller). 
Ichthydium sulcatum (Stokes). 
Lepidoderma squamatum (Dujardin). 
= Chcet. squammatus, Stokes. 
= Chcet. tessellatus Stokes. 
= Chcet. loricattis Stokes. 
Lepidoderma rhomboides (Stokes). 
Lepidoderma concinnum (Stokes.) 
Chcetonotus maximus Ehr. 
= ChcRt. gracilis Stokes. 
Chcetonotus similis Zelinka. 
= Chcet. maximus Stokes, 
ChcBtonotus formosus Stokes. 
Chcetonotus acanthodus Stokes. 
Chcetonotus brevispifiosus Zelinka. 
= Chcet. lanis Fernald and Stokes. 
Chcetonotus acanthophorus Stokes. 
Chcetonotus spinulosus Stokes. 
longispinosus Stokes. 
spinifer Stokes. 
Dasydytes saltitans Stokes. 
Gossea antennigera (Gosse). 
Homologies within the Group of Echinoderms. — Richard 
Senion {Morphol. Jahrbuch, 1889) discusses the homologies which 
occur within the group of Echinoderms. He thinks that in their broader 
features the alimentary canal, enterocoele, water-vascular system and 
nervous system are to be regarded as truly homologous throughout the 
Am. Nat.-Octobcr.-5. 
