ECHINOIDEA. I. 



37 



usual. — The tridentate pedicellariæ are a good deal smaller, but more long-stalked than in D. papil- 

 lata\ the head ca. 0-5™'", the stalk ca. i""" or a little more (PI. IX. Figs. i, 18, 19, 21, 23). The blade is 

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

 below; they join only in tlie i)oint — scarcely the outer half of the blade — and this part of the 

 blade is thcn obliquely cnt off, wliile 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. papillata\ the edge is finely inden ted, and only a few smooth beams cross the cavity of 

 the blade. 



It is a cnrions faet that tridentate pedicellariæ seem to bc wanting in all the (6) specimens of 

 C. affiitis from tin.- Mcditcrranean. ( )n the other hånd they are found in large nnmbers, not only in 

 the ambnlacral areas, ])nt all over the test, in 5 specimens from 33 ' 20' N. Lat. 77" 5' W. L. 90 fathoms 

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

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

 these specimens. Otherwise there seenis 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 P'lorida, but as these are onh- half so large as the specimens from 

 the Mediterranean, it ma\- be taken to bc a difference of age. To judge from the niaterial in liand 

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

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



The spicules of the tube-feet are arrauged as in I), papillata. They are upon the whole a little 

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



The diameter of the test of the largest specimen 38""", the longest sjjine 54""". The colour of 

 this species, as has beeu 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. i. As color forms such an 



unimportant feature in the specific characters of Hchini, niucli stress cauuot l)e laid upon this point , 

 says Agassiz. ( Revision p. 255.) Here, no doubt, it is of souie ini|)ortauce, as ujion the whole the 

 colour niay be an excellent guide for distinguishiug the species, for instance of Echiinis. 



Among the other CY^/fflm-species 6". Rriiii Doderl. seems to be the nearest relation of C. affinis\ 

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

 to be uo important difference in the form of the pedicellariæ in the genus Cidaris\ it will scarcel}' be 

 possible to distinguish the species with certaint\' b)- means of the pedicellariæ, 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 affiiiis will ha\-e to be added to the not few F^chiuids, found Ijoth in the 

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

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

 coast of Southern Europe, and, as has been ob.served above, vStuder's statement (386) of D. papillata 

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

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



