IDYIOPSIS. 



39 



then very gradually. The actmal extremity of the spherosome is 

 slender and exceedingly movable, and the edges of the actinostome 

 can be extended so that it presents the appearance of two distinct 

 lobes. The ovaries and spermaries are much longer sacs than in /. 

 roseola, and not so numerous. The locomotive flappers do not extend 

 as far down the chymiferous tubes as they do in our species, though 

 this difference may only be one of age. Foimd in the Gulf of Georgia, 

 W. T., and in the eastern part of the Straits of Fuca, during the sum- 

 mer of 1859. The habits of this Idyia are somewhat different from 

 those of our species. Instead of the sluggish movements which charac- 

 terize Idyia roseola, Idyia cyathina is very active, and seems to retain 

 the embryonic features of the genus, — short rows of flappers, and 

 great activity in its adult condition. 



Northwest coast of North America (A. Agassiz). 



Cat. No. 287, Gulf of Georgia, W. T., A. Agassiz, 1859. 



IDYIOPSIS Agass. 



Idyiopsis Agass.- Gont. Nat. Hist. U. S., III. pp. 288, 296. 1,800. 



Short vertical axis ; ambulacra very prominent ; interambulacra con- 

 cave ; fringes of circumscribed area arranged in two prolonged circles ; 

 numerous branching tubes arising from circular tube ; compression of 

 the body very striking. (Agassiz.) 



Idyiopsis Clarkii Agass. 



Idyiopsis Clarhii Agass. Cont. Nat. Hist. U. S., HI. pp. 288, 296, Figs. 101, 102. 1860. 



It remains yet to be shown 

 whether the two species of Idyi- 

 opsis here mentioned may not be 

 identical with species of Idyia de- 

 scribed by Eschscholtz as found on 

 the Brazilian coast and in the Gulf 

 of Mexico. The figures of Idyiop- 

 sis given by Professor Agassiz are 

 here reproduced. (Figs. 63, 64.) 



South Carolina (L. Agassiz). 



Fig. 63. 



Kg. 64. 



Fig. 63. Idyiopsis Clarkii seen from the broad side. /, funnel ; l^, P, anterior and posterior 



ambulacra ; P, I', lateral ambulacra ; d, digestive cavity ; o, mouth ; c, the lateral tube. 



Fig. 64. Fig. 63, seen from the abactinal pole, c, circumscribed area; Z', P, I*, Z', lateral 



ambulacra; 1°, l', 1°, Z', anterior and posterior ambulacra. 



