some Species referred to it, 53 



quite different from the smooth surfcice of fig. 2 d. The 

 longitudinal striation dae to the microstructure is seen on the 

 ridges and in the spaces between them. The number of ridges 

 to be detected on one side of the shaft is 13 or 14; but I am 

 unable to see that they occur on the other side of the shaft. 

 The difference in form of the shaft, the different matrix, and 

 the suggestion, obscure though it be, of a different ornament, 

 render it probable that this radiole does not belong to the 

 same species as the other radiole ; and, if either be conspecific 

 with the lecto-holotype of Cidaris Icevispina, it is more likely 

 to be tlie original of Sandberger^'s fig. 2 d. Two other frag- 

 ments, unfigured, are of the same nature as the latter speci- 

 men, and show that the radiole was slightly fusiform, smooth, 

 and finely striate throughout. 



Miss Mary Klem (1904, p. 69) gives as the sole description 

 of this species : " Primary spines cylindrical and ornamented 

 with about twenty-three longitudinal ribs. These ribs are 

 niuricated oppositely." This information is not given by any 

 of the autfiors quoted by Miss Klem, and she does not say 

 that she has herself examined any specimens. Of the two 

 radioles figured by Sandberger, tliat which probably belongs 

 to the species is neither cylindrical nor ribbed ; the other one 

 may possibly have been ribbed, but there is no evidence that 

 its ribs were muricate. 



The holotype of Cidaris scrohiculata Sandberger (their 

 fig. 3j our PI. I. fig. 5) is an interambulacral plate of 

 about the same area as the lectotype of G. Icevispina, but 

 apparently less thick and with a less prominent boss. The 

 niamelon, platform, boss, and scrobicule are of the same 

 general character as in G. Imvispina; but the mamelon is not 

 so much extended, the scrobicular ring Is circular, its tubercles, 

 which show faint traces of scrobiculation, are intermediate in 

 size between the secondaries and tertiaries of G. Icevispina, 

 and appear to have been more regular and more equally 

 spaced. The extra-scrobicular surface was probably smooth. 



The Sandbergers may have been right in regarding this 

 specimen as of a different species ; but if one were to maintain 

 that it came merely from a different part of the test of 

 C, kevifipina, I do not see how that could be disproved. 

 There certainly seems no reason for Desor's suggestion that 

 it may belong to a different genus. 



The systematic position of these two species is doubtful. 

 Since the outlines are not preserved in any of the plates, the 

 only evidence that they belong to a genus with more than 

 two columns of interambulacrals to an area is the a priori 

 evidence afforded by their antiquity. This, however, must 

 be accepted in the absence of proof to the contrary. 



