ECHINOIDEA. I. 



25 



therefore, I tliink it better to refer it to tliis subgenus; the spines, to be sure, show no trace of the 

 widenings peculiar to the two other species, but the not widened spines of the latter are rather 

 similar to those of this species, for which I propose the name of Discocidaris serrata n. sp. 



From st. 192 (Chall.) a specimen is found referred by Agassiz to G. florigcra, which it also 

 resembles rather well (i. e. it resenibles the one figured in Fig. 12, Pctalocidaris florigera). The spines 

 are much richer thorny than in this species; the ambulacral areas almost naked. The pedicellariæ are 

 very peculiar (PL X. Figs. 25, 28). The opening is a long, narrow slit reaching not quite to the point; 

 a powerfully developed end-tooth is found. The small pedicellariæ are essentially of the same structure, 

 the opening only being somewhat shorter and a little broader. Such pedicellariæ have not been 

 found in any of the other known species, and accordingly this species must form a separate genus, 

 for which I propose the name of Schizocidaris with the species Sch. assimilis n. sp.'). 



According to Agassiz (Chall. Ech. p. 43 seq.), Goiiincidaris caiialiciilata is exceedingly varying; 

 he thinks that Cidaris initrix W. Th. must be regarded as one of the many forms of this species, and 

 also that G. vivipara and mcuibrauipora are synonymous with it. After having examined the speci- 

 mens of G. caiialiculata in British Museum I must admit that it really appears as if they all formed 

 only one highly varying species, in which a great number of transitional forms connect the easily 

 recognised extreme forms. If we examine the pedicellariæ, we shall get another conviction; we shall 

 then see that at all events three different .species are found among these specimens referred to G. 

 cnualiculafa. There is a faet that ought to have made Agassiz hesitate in referring them all to 

 one species. He quotes the description by Wyv. Thomson (397) how the eggs of C. iiutrix <are 

 passed along on the surface of the test towards the mouth, and the smaller slightly spathulate prim- 

 ary spines, which are articulated to about the first three rows of tubercles round the peristome, are 

 bent inwards over the mouth, so as to form a kind of open tent, in which the young are developed . 

 Immediately after this quotation Agassiz (op. cit. p. 45) says: The .specimen (PI. II. fig. 2) shows the 

 manner in which they are held in a sort of marsupium bv the foldiug of the abactinal spines over 

 the young crowded upon the abactinal system . Thus in this species not only a nursing of the brood 

 should take place, but the young should even be placed, now round the mouth, now on the apical 

 area. Even if this were not inconceivable, it would have been worthy of remark; but Agassiz has 

 no word of it, though it might seem to impl\- that Cidaris niitrix is really specifically different from 

 Goiiioc. caualiculata. Wyv. Thomson (397 p. 66) also remarks expressly that in G. canalicidata we 

 have the reverse of the faet in C. nntrix: -These spines ... lean over towards the anal opening, and 

 form an open tent for the protection of the young as in Cidaris nntrix^ but at the opposite pole of 

 the body». There is also another faet that ought to raise the suspicion against the interpretation of 

 all these forms as one species: most of the specimens are coast-forms, taken on depths of 3 — 150 

 fathoms; from this there is a far cry to a depth of 1600 fathoms and more. Beforehand it is very 

 improbable that the same species should be found in so varying depths. This faet is not mentioned 

 by Agassiz either. According to my examinations Cidaris uutrix is specifically different from G. 



I) Unfortunately I made no more thorough notes on this specimen, as during my stay at Br. Mns. I had uo clear 

 understanding of the faet that it was a genus quite different from the other specimens called G. florigera. I did not get a 

 clear view of this faet till after my return, when I had examined the pedicellariæ more exactly. The pecuUar pedicellariæ 

 may, however, be sufficient for the Identification of the species, and therefore I do not hesitate to give it a name here. 



The Ingolf-Expedition. IV. l. 4 



