8o ECHINOIDEA. II. 



that its apical .s\stem is like that of P. lagiinciila. evidently its nearest relation. (Loven. On Pour- 

 talesia. PL VII. Fig. 52). 



I have fonnd two kinds of pedicellariæ in P. rosru, viz. ophicephalous and tridentate. The 

 ophicephalons pedicellariæ (PI. XI. Fig. 26) are rather large, with elongated, slender valves. The ter- 

 minal widening is smaller and has fewer teeth than in /-". crratopyga. The tridentate pedicellariæ (only 

 one form fonnd) have simply leafshaped valves ; the endtooth is a little prominent, tlie apophysis con- 

 tinnes into the edges of the blade (PI. XI. Fig. 15). I have noticed especially that the ophicephalons 

 pedicellariæ were fonnd on the fragment of the posterior end ( — abont the tridentate pedicellariæ I 

 have forgot to notice that especially, so they may perhaps belong to the other fragments — ); they 

 are snfficiently characteristic for distingnishing this species from any other of the species hitherto 

 known of this genns — and, evidently, it is the species represented by the anal snont-fragment which 

 mnst keep the name Pourtalcsia rosea, not that represented b)' the fragment with the apical system, 

 which is probabh- no Po?(rt<ilrsia at all. The affinities of Pourtalcsia rosea mnst, of conrse, be left 

 nndecided, so long as we know almost nothing of its shape and strnctnre of test". 



Pmtrtalesia lagiinciila A. Ag. and Tanncri A. Ag. have been treated above (p. 67). 



The question whether all the species referred to the genns Pourtalcsia can rightly remain to- 

 gether in this single genns has repeatedly been treated. In the Challenger >-Report (p. 132) Professor 

 Agassiz comes to the result that all the species mnst remain in one genus, though the character of 

 the test seenis to indicate two natural groups [P. ccratopyga and rosea forming one group, the rest of 

 the species another); in his last great work Tlie Panamic Deep-Sea Ecliini he is inclined to think 

 that <the striking differences fonnd in the varions gronps of species of Pourtalesiæ wonld .seeni to 

 warrant the splitting np of the genns Pourtalcsia into snbsections. We might retain the name of the 

 genus, Pourtalcsia, for the bottle-shaped t}-pes allied to P. >/iira>ida. such as P. Taiiueri, P. lagu>icula. 

 P. Jeffreysi, and form a section of the genus for the elongate P. phiale and another for the stout- 

 tested P. ccratopyga and P. rosea. P. hispida may yet be fonnd to belong to a special genus . (Op. cit. 

 p. 141). Duncan (Revision, p. 285) excludes from the genus P\ iiiiratida and rosea on account of their 

 compact apical system and their postero-lateral interradia being separated dorsally. — Neither Agassiz 

 nor Duncan propose new generic nanies for the subdivisions. Pomel (Classification méthodiqne (324) 

 p. 40) goes more radically to work. He divides the group into four genera. Pourtalcsia is restricted to 

 the species mira^ida, hispida and (?) phiale ; a new genus, Phyalopsis, is established for /-'. laguiicula, 

 another genus, Ceratophysa, for P. rosea and ccratopyga. and a third genus, Pliyalc, for P. Jeffreysi and 

 proljabl)', P. Carina ta. 



I cannot agree with any of these proposed divisions of the genus; especially those proposed 

 by Pomel seem to me very unfortunate and quite in disaccordance with the natural relations of the 

 species. Also Dune an' s exclusion of /-'. luiraiida from the genus Pourtalcsia is very unfortunate, first 

 becanse it is the t>pe species of the genus, and further becanse its apical system is, in all probability, 



I De Meijere (Siboga-Ech. p. 169) finds the statement that the liivial ambulacra are in niutual contact only on the 

 abactinal side <>so dass das Sternum hochstens von den heuachbarten Anibulacren unterbrochen sein kann in D vin c an 's 

 remarks Op. cit. p. 281. As far as I can see this is not the nieaning of Duncan, on the contrary, he probably nieans to say 

 that in P. rosea and tniraiida there is no contact on the abactinal side between the two postero-lateral interradia. In any 

 case no new information on the structure of these Ivvo species is given there by Duncan. 



