ECHINOIDEA. I. 



35 



The statements that it has been taken in the Red Sea (Rnsso 348), at the Canaries, the West 

 Indies, St. Paul, La Plata, and even at the Philippines, it will be best for the present to leave out of 

 consideration, until a renewed examination of the material from these localities has been made. The 

 statement that it is found at the Philippines, is made by Agassiz (Chall. Ech.); but he has himself 

 expressed a doubt as to the correctness of the determination -- and with good reason. I have in 

 British Museum had occasion to examine the two specimens from the Philippines (Chall. sts. 204 and 

 210), and have found the one from st. 204 to be a Cidaris sp., and that from st. 210 a Stereocidaris sp. 

 (I could not enter into a determination of the species.) The statement by Studer (386) that it has 

 been taken at the Cape Verd Islands, must no doubt apply to Cidaris affinis \ he remarks that the 

 small spines were of a scarlet colour, which agrees with C. affinis, but not with D. papillata. I am 

 also fortunate enough to be able to correct the statement by Russo that it is found in the Red Sea, 

 as Prof. Monti celli has sent me the specimens for examination -- they are Cidaris baculosa. 



2. Cidaris affinis Phil. 



PI. I. Fig. i. PI. VI. Figs. 9-10. PI. VIII. Fig. 2. PI. IX, Figs, i, 89, 11 12, 1719, 21-24. PL XI. Figs, i, 22. 



Synonym : Cidaris Stokcsii L. Ag. & Desor. 



Dorocidaris neapolitana! Ramsay 331. 



A. Philippi: Beschreibung einiger neuen Echinodermen nebst kritischen Bemerkungen iiber 

 einige weniger bekannte Arten. Arch. f. Naturgesch. 1845. I. p. 351. L. Agassiz & E. Desor: Cata- 

 logue raisonne des families, des genres et des especes de la Classe des Echinodermes. Ann. Sc. natu- 

 relles. 3 Ser. VI VIII. 184647. -- M. Sars: Middelhavets Littoral-Fauna, p. no. -- Wyv. Thom- 

 son: Echinoicls of < Porcupine* (395). p. 726. PI. LX. 



Ks ist mir unbegreiflich, dass man nicht schon langst die C. affinis von der C. hystrix unter- 

 schieden hat, da sie sich auf den ersten Blick durch dunkler rother Farbung und kiirzere, spitzere und 

 rauhere Stacheln auszeichnet -- und bei Neapel gar nicht so sehr selten ist, says Philippi (op. cit. 

 p. 352). It is still more inconceivable that later authors (Agassiz, Ludwig, Bell, a. o.) have reunited 

 the two species. Wyv. Thomson himself is somewhat in doubt whether C, affinis is really speci- 

 fically different from Doroc. papillata. By a thorough examination it is seen that they are not only 

 two well separated species, but that they even belong to two different genera. C. affinis is to be 

 referred to the genus Cidaris s. str., its nearest relations being C. Reini Doderl., metularia Lamk. 

 Thonarsii Val. etc. -- Although the northern boundary of this species is scarcely found so far north 

 that it occurs in the territory the Echinid-fauna of which is treated in the present work, I nevertheless 

 think it necessary to give a careful description of it, partly to prove my assertion that it has nothing 

 to do with Doroc. papillata, but especially to prevent the two species being intermingled in future, as 

 they have been so long, to the great injury of the study of the geographical distribution of these 

 species. In the description those features are especially emphasized, in which it differs from D. 

 papillata. 



Iii the form of the test, the breadth of the ambulacral and the interambulacral areas, the 

 number of ambulacral plates for each interambulacral plate (1012), there is scarcely any difference of 

 importance between this species and D. papillata. The interambulacral plates (PI. VI. Fig. 10) are here 



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