ECHINOIDEA. I. 



groupera naturellement tin assez grand nombre d'especes vivantes et fossiles et me parait utile a 

 conservers. The advantage of such a <genus, however, seems to me to be rather illusory; with the 

 limitation given by de Loriol Rhabdocidaris becomes still more heterogeneous than Phyllacanthus, 

 as it is limited by Agassiz in Revision. As the genus has originally only been used of fossil 

 species, it is quite impossible to decide whether some of the recent forms really belong to it; by the 

 tests and the spines alone the genera cannot at present be recognised with certainty, and no pedicel- 

 larize of fossil species are known. Accordingly the name of Rhabdocidaris is not to be used for any 

 recent Cidarid. 



On the other hand the other species with terminal opening on the globiferous pedicellarise 

 and limb on the stalk seem to form a natural group; the shortness or length of the limb can 

 scarcely be used as a character for the subdivision of the group. Possibly C. affinis and Reini (and 

 perhaps panamcnsis) will prove to form a special group -- their spines seem to differ somewhat from 

 the other mentioned species; but this can only be decided by more thorough examinations. For the 

 present all these species: Cidaris afftnis, Reini, (panamensis ?), tribuloidcs, galapagensis, metularia, Thou- 

 arsii, vcrticillata, and baculosa 1 } must form one genus, which must keep the old name of Cidaris, 

 Lin ne's 'iEchimis Cidaris*, as has been proved by Loven (252), being Cidaris baculosa Lamk. The 

 name of Eucidaris Pom el, which has of late often been used for species of this group, cannot correctly 

 be used. Pom el (324) enumerates as types of this genus some fossil forms (moricri etc.) from the trias, 

 and trois especes vivantes, but he does not mention which species he means, and the fact is here, 

 as in Rhabdocidaris, that it is quite impossible to decide whether any of the recent species belong to 

 the same genus as the mentioned fossil ones. 



Besides the species mentioned here, Doderlein still enumerates iL&ocidaris* annulifera Lam. 

 as belonging to those species, the globiferous pedicellariae of which have terminal opening and limb 

 on the stalk ; -here C. annulifera is referred to the genus Stephanocidaris which has a quite different 

 form of pedicellarise (see above) - - a contradiction which can only have its origin from a difference 

 in the interpretation of the species C. annulifera Lamk. This species together with C. baculosa Lam. 

 have caused and still cause many difficulties to the systematists. Lamarck 2 ) in his diagnosis of 

 C. annulifera says: <spinis majoribus longis, tereti-subulatis, asperulatis, albo purpureoque annulatis, 

 and in his diagnosis of C. baculosa: spinis majoribus subteretibus, tuberculato-asperis, apice truncatis, 

 collo guttatis; according to this Agassiz (Revision of Echini* p. 389) states as the only certain 

 character of the highly varying C. baculosa <-the spotted base of the shaft of the spine below the 

 milled ring, which is of a light reddish or reddish-yellow ground-color, with deep violet spots marked 

 extremely distinctly upon the fine longitudinal striation. Loriol (243) later describes and figures a 

 Cidarid by the name of C. aniiulifi-ra Lamk.; he has had a radiole of the type-specimen of this species 

 for comparison, and has found it completely corresponding to those of the specimen described by him. 

 These spines have leur base couverte sur line longueur plus on moins grande de petites taches 

 pourpres, formant des lignes et entremelees de petits points* - the character especially particular of 

 C. baculosa ! Thus, somehow or other, an error must have slipped in, and I think it most likely that 



') If C.pistillaris Lamk. be a good species, it must also be referred here. 



2 ) Histoire naturelle des animaux sans vertebres. II. Ed. 1840. T. III. p. 380. 



3' 



