B04 , T. A. STEPHENSON 



Genera : Discosoma, Paradiscosoma, Eicordea, 

 r i 11 i a , K li o d a c t i s , A c t i n o t r y x . 

 Discosoma, Leuck., 1H2H. 



Discosomidae with tentacles all of one sort, not branched, not knobbed, 

 may be swollen towards the tips; short, usually wart-like, sometiniCB 

 reduced or even vanished, so that only traces of them remain as endo- 

 dermal evaginations in the mesogloea of the disc. Margin of body 

 straight or more or less notched or irregular. Tentacles in radial rows 

 on at least some endocoels, sometimes on exocoels too. Sphincter absent 

 or weak diffuse. 

 Species : 



D. nummiforine, Leuck., 1828, p. 3. (See Simon, 1892, and 



Carlgren, 1900, p. 62.) 

 D. Yuma. Carlgr., 1900, p. 63, 

 D. Unguja, Carlgr., 1900, p. 64. 

 And probably others. 



I do not. feel clear that all the genera that follow are really 

 distinct from Discosoma, but am listing them in full. 

 Taking the family as a whole, the two clearest genera are 

 Discosoma and Actinotryx. Beyond this there is less 

 certainty, lihodactis is probably distinct but is little 

 known. Eicordea and Paradiscosoma seem doubtfully 

 distinct from Discosoma. Even Oriuia might be only 

 a curious state of Discosoma, but is more likely to be 

 distinct than the others: even in Paradiscosoma one 

 sometimes sees the tentacles collapse on themselves so that 

 they form little double-walled cups, and it would not take much 

 to make this into Orinia ; and McMurrich says some of the 

 more peripheral of them are tuberculiform and not crateri- 

 form. If there is a naked zone between the marginal and 

 discal sets, however, that will clinch the distinction. There 

 are other genera and species which have been referred at one 

 time and another to this family, before it was properlj^ under- 

 stood, but these have been cast out as time went on, and are in 

 this paper referred to their new positions, e. g. Stoichactidae. 



Paradiscosoma, Carlgr., 1900, p. 60. (n. nom. for Isaura.) 

 Discosomidae with margin of disc thrown into small lobes. Otherwise 

 like Discosoma. (Sec Part II, Text-figs. 3. C, b, 5,) 



