j,Q ECHIXOIDEA. II. 



more numerous than in cordaiutn. It may be remarked that mtstrale reaches tlie same considerable 

 size as cordatum. A specimen of 74™™ length, from Victoria, is in the Museum of Copenhagen. — After 

 all, the conclusion seems inevitable that Ech. australc is really synonymous with Ecli. cordatum, which 

 species thus has an almost cosmopolitan distribution; only along the Pacific Coast of America it does 

 not seem to occur. 



In the <:Challenger»-Echinoidea (p. 174) Ech. aiisfrale is recorded from a depth of no less than 

 2675 fathoms (St. 234), which seems, indeed, very curious, the species being otherwise a littoral form 

 of rather small bathymetrical distribution. I have examined the specimens from this station in the 

 British Museum, and I must agree that they really seem to be identical with the littoral specimens. 

 Perhaps the actinostome is a little more central than in the littoral specimens, but otherwise they 

 seem to agree in all essential points. That the pores of the odd ambulacrum are as }-et only placed 

 in a single series does not give any distinguishing character, since the same is the case in cordahim 

 and australe of a similar size (the largest of the deep-sea specimens is only 15""" with the genital pores 

 just about to appear). Of pedicellarias only a small tridentate and some triphyllous were found; they 

 agree with australc, and the same is the case with tubefeet and spicules. Since, however, only small 

 specimens are represented, I think it safer to regard it as not beyond doubt that these deep-sea spe- 

 cimens are really the same species as the littoral atistrale. And upon the whole it might well be 

 thought possible that by a very careful examination of a large material of this form from the different 

 localities in the Atlantic and the Indo-Pacific, characters might be found by which it might be divided 

 into different recognisable species. In that case this group might well be regarded as a distinct genus, 

 characterized by its deep anterior ambulacrum, with the pores arranged in double series. Also the 

 peculiar tripln-llous pedicellarise would then form one of the generic characters. For the present, how- 

 ever, it seems that tliis group forms really only one species — the onlv littoral species of Echinoidea 

 hitherto known with such extensive, almost cosmopolitan distribution. (The Diadcma saxatilc and 

 Echinus norvegicus hitherto regarded as almost cosmopolitan are really not so widely distributed, as I 

 have shown)'. 



A few remarks may here also be given of the last of the Echinocardhim-s'^GCiQS hitherto known, 

 the Ech. mediterraneuvi Forbes. A very careful description has been given of this species by Koehler 

 (Sur les Echinocardium de la Mediterr. p. 175. PI. 4. 1—4, 14), but a few points of some importance 

 may still be added. The labrum reaches the second adjoining ambulacral plates, which send a narrow 

 forward prolongation to meet its corners. Three pairs of plates (one or two pairs of pores) are included 

 by the subanal fasciole. The pores of the odd anterior ambulacrum are small aiul distant; the plates 

 included by the internal fasciole are very narrow. The fasciole goes rather far behind the apical system, 

 passing over the 5— 6th plates of the odd interambulacrtnn in a specimen of 28""" length. These iuter- 

 ambulacral plates within the fasciole are very narrow, especially those traversed by the fasciole, and there 

 is a rather abrupt widening of the plates just outside the fasciole (Fig. 25). It may also be expressh- 

 stated that no larger tubercles are found above the ambitus in the anterior interambulacra. A curious 

 feature, which I have not seen in any of the other species of this genus, is that the clavulce cud in 

 two small lobes of skin, the point otherwise being almost not widened (PI. XVII. Fig. 51). The pedi- 



' Ingolf-Echiuoidea. Part I. Siaui-Echinoidea. Part I. 



