120 ECHINOIDEA. II. 



out this grouping more exactly. Recently Four tan (Op. cit. p. 433) establishes two groups in the 

 genus Schizaster, founded on the arrangement of the pores of the anterior ambulacrum, viz. 1. the 

 Sch. caualferus-gronp with these pores biserially arranged, and 2. the Sch. fragilis-gTOup with the 

 pores arranged in a single series. He does not mention which species he refers to each group. 



Before entering on a discussion of this question of the subdivision of the genus Schizaster I 

 must give a few synonymic remarks on some of the species. As pointed out by Loven (Echinoidea 

 descr. by Linnaeus, p. 168) the Schizaster Japouicus A. Ag. is identical with Linne's Echinus lacunosus; 

 the species will then have to be named Schizaster lacunosus (L.). With this species I find further to 

 be synonymous the Sch. ventricosus Gray. This seems, indeed, quite improbable, judging from the 

 figures of Sch. Japonicus and ventricosus given in the « Challenger -Echinoidea PI. XXXVI; the two 

 forms figured there are, I quite agree, distinct species, but the species represented in Figs. 1 — 3 is not 

 ventricosus Gray, it is probably identical with the Sch. latifrons A. Ag. described in the Panamic 

 Deep-Sea Echini*. (This will be verified in Part II of the «Siam-Echinoidea »). On the other hand 

 I cannot agree with Professor Agassiz in regarding Sch. Jukes ii Gray as a synonym only of 

 lacunosus (ventricosus), I even think it more probable that it will have to be referred to another 

 genus (Periaster), as has been pointed out above (p. 108). — The matter: Schizaster gibberulus — 

 Savignyi has been cleared up by Fourtau (Op. cit); I quite agree with him in this question. Finally 

 I may notice that the Sch. ajfinis Studer named in Broun p. 1392, is, according to a communication 

 to me in a letter from Dr. Meissner, the same as Sch. capcusis Studer. The recent species hitherto 

 known of the genus Schizaster are thus: Sch. lacunosus (L.), canaliferus (Lmk.), orbignyanus A. Ag., 

 Edwards/ Cott, Savignyi Fourtau, gibberulus Ag., Philippii (Gray), fragilis (Dub. Kor.), Moseleyi A. Ag., 

 capensis Studer, autarcticus Doderl., latifrons A. Ag., Townscndi A. Ag. 



If we regard the shape of the test of the different *SV///,crff.s'/V;--speeies, we will at once find 

 them to form two distinct groups. In the one the test is high and the ambulacra rather much deepened, 

 in the other the test is low and the ambulacra only slightly deepened. To the former group belong: 

 5". canaliferus, orbignyanus. Edwardsi and lacunosus; to the latter: S. fragilis. Moseleyi. capensis. lati- 

 frons, Townscndi, autarcticus and Philippii. A third group is perhaps formed by the species gibberulus 

 and Savignyi. If we now review the more important characters of these species, we shall find the 

 species of these groups to agree also in other important features, viz. the number of genital pores 

 and the structure of the globiferous pedicellarire. In the cana/iperus-gxou^ there are two, in the fragilis- 

 group three genital pores. To be sure the statements of Agassiz regarding the genital pores of «Sch. 

 ventricosus> and < Sch, Japonicus- do not agree with this; but these statements are based partly on 

 wrong determinations. D e s o r (Synopsis des Ech. foss. PL 43. 2 a) figures the apical system of a Sch. 

 canaliferus with three large genital pores; but this is evidently an abnormal and seldom occurring 

 case: the third pore is in the posterior interambulacrum, not in the anterior left genital plate as in 

 the other species with 3 genital pores. (To declare the figure to be wrong, as is done by Tornquist 1 

 seems rather hardy, as the figure is evidently very carefully drawn). In (Catalogue raisoune (p. 121, 

 Note) Iy- Agassiz says: Je connais des iudividus d'une meme espece (Schizaster lacunosus), dont les 



1 Die Beschaffenheit des Apicalfeldes vou Schizaster und seine geologische Bedeutung. Zeitschr. deutsch. geol. Ge- 

 sellsch. 55. 1903. p. 377. 



