BCHINOIDEA. I. 37 



usual. — The tridentate pedieellari;e are a good deal smaller, but more long-Stalked than in I >. papil- 

 lata; the head ea. o-5 mm , the stalk ca. i""" or a little more (PI. IX. Figs, i, 18, 19, 21, 23). The Made is 

 somewhat slenderer, and when the pedicellaria is shut there is a wide open space between the blades 

 below; they join only in the point -- scarcely the outer half of the blade and this part of tin- 



blade is then obliquely cut off, while in I), papillata the whole edge of the blade forms a chiefly 

 straight line. For the rest the construction of the blade is far more simple and less complicate 

 than in D. papilla fa ; the edge is finely indented, and only a few smooth beams cross the cavity of 

 the blade. 



It is a curious fact that tridentate pedicellarise seem to be wanting in all the (6) specimens of 

 C. a/finis from the Mediterranean. On the other hand they are found in large numbers, not only in 

 the ambulacral areas, but all over the test, in 5 specimens from 33 20' N. Lat. 77 5' W. L. 90 fathoms 

 (near Florida), which our museum has received from U. S. Fish Commission (Smiths. Inst.) under the 

 name of Dorocidaris papillata, var. In return the large globiferous pedicellarise are extremely few in 

 these specimens. Otherwise there seems to be no other difference of importance between these speci- 

 mens and those from the Mediterranean. To be sure the spines (PI. VIII, Fig. 2) are comparatively a 

 little longer in the specimens from Florida, but as these are only half so large as the specimens from 

 the Mediterranean, it may be taken to be a difference of age. To jndge from the material in hand 

 I must, at all events, regard them as being the same species, while I do not venture to decide, 

 whether a distinction may be made between a Mediterranean variety and an Atlantic one. 



The spicules of the tube-feet are arranged as in D. papillata. They are upon the whole a little 

 more spinulous than in this latter, but the difference is extremely slight (PI. XL Fig. 22). 



The diameter of the test of the largest specimen 38'"'", the longest spine 54™"'. The colour of 

 this species, as has been observed by all the authors that have taken it to be a separate species, is 

 lively red; the spines are brownish, with darker and lighter bands. The colour keeps rather well in 

 spirit, sometimes excellently, as in the specimen figured on PI. I. Fig. 1. - As color forms such an 

 unimportant feature in the specific characters of Echini, much stress cannot be laid upon this point , 

 says Agassiz. (Revision p. 255.) Here, no doubt, it is of some importance, as upon the whole the 

 colour may be an excellent guide for distinguishing the species, for instance of Echinus. 



Among the other Cida ris-species C. Reini Doderl. seems to be the nearest relation of C. af finis ; 

 thev have both of them slender spines and a little limb on the stalk of the pedicellarise. There seems 

 to be no important difference in the form of the pedicellarise in the genus Cidaris; it will scarcely be 

 possible to distinguish the species with certainty by means of the pedicellarise, but there seems also 

 to be characters enough to be got from other features. The spines especially show a rather great 

 richness in forms in this genus. 



Accordingly Cidaris a f finis will have to be added to the not few Echinids, found both in the 

 Mediterranean and at the eastern coast of America. As to its distribution in other places only little 

 can be said, as it has been intermingled with D. papillata. No doubt it will be found at the Atlantic 

 coast of Southern Europe, and, as has been observed above, Studer's statement (386) of D. papillata 

 being found at the Cape Verd Islands must surely apply to C. affinis. That it will also be found at 

 the Azores, ma}- be said with some certainty. It seems to be a more littoral form than D. papillata \ 



