ECHINOIDEA. II. 105 



of the test of this species. But it seems beyond doubt that in the Challenger) Report two separate 

 forms were included under '^Flemtaster zonattisy. one (St. 8|, evident!}' the figured one, a true Hemiasier 

 and e\'en the same as //. rxpergthis, the other (St. 126) probably a Schizaster, which will certainly 

 prove to be a new species. The name Iloiiiaster zonahis ought then certainly to be dropped as a 

 sNiionym of //. cxpergitus. 



Hemiaster Mentzi A.. Kg. has unfortunately not been figured by Professor Agassi z, and from 

 the description (: Blake:>-Echini. p. 66) it is quite impossible to see by which characters it is disting- 

 uished from //. expcrgitus, the onl}- feature not agreeing very well with the latter species being the 

 ^narrow, comparatively elongate space included within the peripetalous fasciole». — From the U. S. 

 National Museum I have received for examination a large specimen of //. Mentzi; it is certainly 

 identical with //. cxprrgifiis. Of course, I cannot state with certainty that it is the true //. Mnifzi. I 

 have seen; but I ha\-e no reason to doubt the identification. Until the contrar\- is proved I must 

 then regard //. Mentzi as a synon\tn only of //. cxpergitus. — From //. gibhosus it is stated to differ 

 in having a larger number of buccal plates, a feature which I do not find to hold good by comparing 

 the specimen of gibbosiis from the <Siboga-> with the specimen of //. Mentzi or with expcrgitus. 



Hemiaster fiorigeriis Studer differs from expcrgitus in several respects, judging from the de- 

 scription and figures given by Studer (Echinoidea d. Gazelle. (386) p. 882. Taf. 11. 3). The test is 

 broadest in the middle, not in the anterior end as in cxpergitus, and the height of the posterior end 

 is evidently smaller than in the latter species.' According to the description the anterior petals are 

 the shorter, but this is in contradiction to the figures 3 a and 3 c. The apical system, according to 

 the Fig. 3 d, is ethmol)-tic, a very important character, so important, indeed, that it must certainly 

 exclude the species from the genus Hemiaster. (Dr. Meissner kindly informs me that .Stnder's 

 description of the apical system is correct). The two anterior genital pores are 

 distinctl}- smaller than the posterior: in cxpergitus they are of equal size. The 

 relation of the labruni to the adjoining ambulacra cannot be seen from the figures; 

 but Dr. Meissner informs me that the labrum ends off the first ambnlacral plate. 

 (Fig. 20). By a short examination of the type-specimen during a visit to the Berlin- 

 Museum I found two sorts of pedicellarite, viz. tridentate and rostrate. The former 



^ Fig. 20. Lalirum and 



(PI. XV. Fig. 23) are essentially like the large form of tridentate pedicellariae in adjacent ambnlacral 



AT^, 1- 11 • i-rr 1 1-^.1 r ^1 plate of /Umiai/er 



cxpergitus, but only 0-2™"'. The rostrate pedicellarue differ only very little from the jiori^enis. (From a 



form with the small end-part of cxpergitus. The spicules of the frontal tube-feet sketch by Dr. M. 



M u i s s n e r ). 

 (PI. XV. Fig. 28) are more nmnerou.s, larger and more thorn}- than those of expcr- 

 gitus. They are arranged in two close series; on one side those of both series ha\e their ends inter- 

 mingled, on the other side they leave a bare space between them — just as has been described and 

 figured for Dorocidaris peipillata (Part I. p. 33. PI. MIL Fig. i). — That H.florigcrus is a distinct species 

 is beyond doubt, but it is ver>- dotd^tful if it can remain in the genus Hemiaster, on account of its 

 ethmolytic apical system. However, as long as the species is so unsufficiently known it will scarcely 

 be possible to determine with certainty to which genus it ought to be referred. 



I Studer gives the following measurements: Length 24min, Breadth 2i'nni_ Height 13mm. i,, //. expergHus of a corre- 

 sponding size the measurements are: Length 20m"', Breadth 201""', Height i6-5mni. 



The Ingolf-Expedition. IV. 2. I4 



