6 PROCEEDINGS OF THE NATIONAL MUSEUM Vol. 83 



than calling attention to the figure. I have seen a similar structure 

 in Crotalocrinus eora Hall in the collections of the United States 

 National Museum. Here instead of the normal anal plate two 

 subequal plates rest on the posterior basal. 



Were the structures figured by Angelin correct, I still would not 

 subscribe to Bather's explanation that anal x had fused with the 

 posterior basal. Absent it might be, but as in the case of the specimen 

 of Crotalocrinus cora I would rather assume that a tube plate had 

 migrated downward to a level with anal x. I agree that so far the 

 Same explanation might be given for the structures found in Lecytho- 

 crinus and Corynecrinus. In this case Miiller's type would be con- 

 sidered the norm and the two plate condition variants from the 

 normal structure. 



I suggest, however, that the anal structures of the Lecythocrinidae 

 may have evolved from a type essentially like those found in the 

 Gasterocomidae, crinoids to which I believe the Lecythocrinidae are 

 closely related. The lateral anal opening of such a form as Gastero- 

 coma may notch the distal face of the posterior basal or be separated 

 from it by small plates. In one specimen of Gasterocoma antiqua 

 Goldfuss in the Springer collection two plates rest on the upper sloping 

 shoulders of the posterior basal. A posterior view of the specimen 

 could easily pass as a view of Lecythocrinus in which the ventral tube 

 had been broken away. In some specimens of Gasterocoma there is a 

 well-defined anal pyramid of small plates much like the structures to 

 be found in certain of the early Cyathocrinoidea such as Carabocrinus. 

 It seems to me quite reasonable that the ventral tube of the Lecytho- 

 crinidae might have arisen as a simple prolongation of such an anal 

 protuberance. Subsequently a single tube plate may have become 

 centered on the posterior basal, as I conceive to be the case in Miiller's 

 type of Lecythocrinus eifelianus, and give a remarkable simulacrum 

 to a true anal r. 



