98 



ECHINOIDEA. I. 



not serrate, and that the apophysis does not widen to a cover-plate, contrary to the triphvllous pedi- 

 cellariæ of the Echinothiirids. All fonr kinds of pedicellariæ are certainly fonnd in every species; bnt 

 of some species individuals niay often be fonnd, where globiferons or tridentate pedicellariæ (sometimes 

 both forms) are qnite wauting or very few in nnmber (for instance Ecliiniis Alexandri). This faet, 

 of course, is an unfortunate circumstance, but the valne of the pedicellariæ as systematic characters 

 are not otherwise lessened by it. 



If we now examine the genera and species referred to <TriplecJiiiiidiT and 'iEc/iinoi/icfradæ.'' 

 with special regard to the featnres described above, we shall get a view of tlieir relations very different 

 from the views expressed in the above mentioned systems. 



The genus Ecliiinis is notorious for its difficnlty. A great many species have been described, 

 bnt most freqnently the descriptions are insnfficient, so that the species cannot be recognized by them. 

 One species, Ech. aciitus^ is very varying, and has occasioned the establishing of a great nian\' 

 «species», which nobody has been able to recognize with certaint\-, and by which the confusion has 

 onh" been increased. But even excellent!}' characterized species, as for instance E. clegans^ have often 

 been confounded with other species, what I have repeatedly been able to substantiate; what is hitherto 

 stated with regard to the distribntion of the Echmus-s^&c\&s, must accordingly be used with great 

 cantion. The reason of all these difficnlties is almost exclusively to be fonnd in the literature: an 

 exact examination of the auimals themselves shows that the species upon the wliole have ratlier 

 distinct characters. 



The following species are referred to the genus Ecliiinis: iniliaris Miill., niicrofiiberculatus Blv., 

 angulosus (Leske), csculcnfns L., acnfiis L,amk., norvcgicits Diib. Kor., Eloniiigii Forb., )iiicrostoi)ia W>'\'. 

 Thoms., iiiclo Lamk., elegaiis Diib. Kor., gracilis Ag., Wallisi Ag., htcidus Doderl., Robillardl Loriol, 

 darnleyensis Woods, magellaiitais Phil., margaritacciis Lamk., //orridiis Ag., Alexandri Dan. Kor., albo- 

 cinctus Hntton, diadema Studer, Neiimayeri Meissiier, multicolor Yoshiwara. A great many older names 

 are cited as synonyms to several of these species in Agassiz's «Revision of Echini ; a renewed exami- 

 nation of the type specimens of these « .species with e.special regard to the pedicellariæ might perhaps 

 give other results than those of A g a s s i z ; bnt until such examiuations have been made, we must build 

 on the results laid down in Rev. of Ech... Of all the above mentioned species, with the exception 

 of Ech. multicolor.^ I have had occasion to examine authentic specimens, of Ecli. horridits.^ Åh'm>myen\ 

 and Alexandri even the tyjje specimens. The result is a considerable reduction of the number of 

 species in the genvis Eckiiiiis, some of the mentioned species being dropped as synonyms, some prov- 

 ing to belong to other genera. 



As the type of the genus Echinus E. csculcntits must be put down, the only one of the species 

 established by Linné. Of its characters the following ones must be mentioned here. Only every 

 other ambulacral plate carries a primary tubercle (in large specimens often 2 — 3 piates without primary 

 tubercle foUow each other). All the ocular piates are shut off from the anal area. The buccal mem- 

 brane with nnmerous small and larger piates; spines on the buccal piates. The globiferons pedicellariæ 

 without neck, the blade with a lateral tooth on either side, the edges connected across the inside. 

 The tridentate pedicellariæ (PL XVIII. Fig. 20) long, narrow, the edge set with nnmerous small teeth 



