﻿82 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



[VOL. 47 



Calyx Abnormalities in Camerate Crinoids 

 It is worth}' of note that we have in this comparatively small collec- 

 tion a relatively large number of abnormal individuals. If the 

 more unusual of these, such as Megistocrinus sphceralis n. sp. and 

 Dolatocrinus asterias n. sp., had occurred as isolated specimens, they 

 would doubtless be considered representatives of new genera, but 

 they are associated with a series of forms having a peculiar surface 

 or other feature by which their relationship can be determined. This 

 being true for the more extreme forms, cases in which the abnor- 

 mality is confined to a single plate may reasonably be accounted for 

 in the same way. Mention of abnormal individuals has occa- 

 sionally been made by other students of the Crinoidea. Bathers- 

 considers the type of Mitrocrinus as probably an abnormal in- 

 dividual. Miller and Gurley state, with reference to Dolatocrinus 

 ornatus Meek, " In one ray of the typical specimen the second radial 

 is abnormally wanting, while the other is larger than usual," etc. 

 The occasional presence of such abnormal individuals does not 

 destroy the force of the rule calling for a definite number of basals 

 and radials in each species, but it is of interest as showing the amount 

 of variation which may occur within the limits of a species, and is 

 probably no more than could be found among recent organisms. 



A table is appended showing the geological and geographical dis- 

 tribution of the crinoids studied in the preparation of this paper. 



Table Showing the Distribution of Devonic Crinoids as Illustrated by the 



Collections of the United States National Museum and 



the Massachusetts Institute of Technology. 



1 A Treatise on Zoology, ed. E. Ray Lankester. 



