THE CRINOIDEA 



127 



simulating that of primitive orals (e.g. Gissocrinus, Fig. XLL, Crotalo- 

 crinus, Fig. XCII. ; cf . Eublastoidea). Other ambulacrals, especially 



FIG. XXXVIII. 



Tegmen ofEuspirocrinvs spiralis, showing four cordi- 

 form deltoids or orals, and a mudreporito, with ambu- 

 lacrals overlying their apposed edges, lu the pos- 

 terior interradius is the base of the broken oft* anal 

 tube. (From Bather, 1893.) x 3. 



Fio. XXXIX. 



Teamen of Citathocrinus. 1, C. 

 plaints with ambulacrals and inter- 

 ambulacrals removed, exposing 

 app'-r.-j-J edges of orals (A) and 

 madieporite (M). 2, C. mammillae-is 

 with ambulacrals (rj>) and interam- 

 bulacrals (in) almost entirely cover- 

 ing orals (A) and peristome. (From 

 Bather, 1892.) x 2. 



axillary Amb, increase in size, and form prominent bosses on the 

 tegmen, called "radial dome-plates" (Fig. XLIL); the effect of 

 this is enhanced by the sinking of the other ambulacrals (e.g. 



Fio. XL. 



Cylwocriniis nodosus, to exemplify the simplest 

 type of Camerate tegmen. 1, from 1. post, radius ; 

 2, from above. As, anus ; !', basals ; br, opening 

 for food -groove and underlying canals; ib, large 

 interbrachials (suborals, Jaekel). Other letters as 

 usual. (Ai; ,;.,r Joh. Miiller, 1855.) x 2. 



XLL 



Tegmen of Gissocriniis arthriticus, 

 showing ambulacrals (Amb) passing 

 down arms and over apposed orals 

 (0),and becoming enlarged over peri- 

 stome. Post. O remains as a folded 

 madreporite; t, anal tube. Other 

 letters as usual. (From Brit. Mus. 

 46457.) X 3. 



Actinocrinidae). These two facts suggest that the proximal dome- 

 plates of Camerata, regarded as orals by Wachsmuth & Springer, 

 and so quoted under head (3), may after all be ipr-^nsd ambulacrals. 



