ECHINOIDEA. I. 6l 



To tilis genus belongs further one specimen (or more?) from Chall. st. 272 detennined by 

 Agassiz 3.S P/wriiiosoiJ/a tcmic/ — The spiciiles (PI. XI. Fig. 18) are as in K. astcrias and arranged in 

 the same wa\-; no sucking disk. I can gi\e no information of the faet whether the spines are as in 

 K. asterias, as I have no notice of this feature. The pedicellariæ are ver>- similar to those of K. astcrias^ 

 but here moreover a larger form of tridentate pedicellariæ is found (PI. XIII. Fig.s. 15, 21), which I 

 have not seen in the t\-pe specimen of A'. astcrias. As, however, the pedicellariæ agree otherwise so 

 exactly, it mav be supposed that this form will also be found in A'. astcrias. This larger form of 

 pedicellariæ is chiefly constructed as the smaller one; the cover-plate has only a few holes in the 

 median line, or is quite open the edges not joining completeiy. The point is a little widened, broadly 

 hastate, with exceedingly finely serrate edge; (as in the triphyllous pedicellariæ the serrations are only 

 to be seen under very higli magnifying powers); the holes in the blade are beautifully arranged in 

 curved series. They are very long-necked; the head up to o-8™"'; the stalk is of the structure char- 

 acteristic of the genus Kainptosoina. The smaller form of tridentate pedicellariæ resemble to a high 

 degree those of A'. astcrias the only difference being that the apoph\-sis and edges have no thorns. 

 The triplndlous pedicellariæ are somewhat shorter and more arched than those of K. astcrias, biit they 

 have the same peculiar cover-plate, and the serrations of the edge are likewise exceedingly slight. — 

 There can be no doubt that this species also belongs to the genus Kaiuptosoiita; but it may be 

 doubtful whether it is a separate species, or identical with A'. astcrias. The small differences in the 

 pedicellariæ are suggesti\-e of its being a distinct species; but this question cannot be decided with 

 certaintv, till a direct comparison of the two specimens has been made. 



Xow we have only left two of the species referred to Pliorniosoma, viz. Pli. panavioisc A. Ag., 

 and Pil. Iiispidtini A. Ag. As to the former it has been supposed above that it may be a genuine 

 PhoriiiPsoiJia, of the latter nothing at all can be said. Both species have only been preliminarily and 

 very incompletely described. 



The genus Spcrosoiiia established by Koehler (228, 229) is especialh' characteristic by the 

 peculiar construction of the ambulacral areas on the actinal side. The secondar\- ambulacral piates 

 are of about the same size as the primary ones; the primar\- ambulacral plate is divided into an outer 

 part, in which the pore is found, and an inner part. Thus on the actinal side the ambulacral area 

 consists of 8 series of piates. The tulje feet are placed in three widel\' separated series. The spicules 

 are large fenestrated piates, not arranged in series; there is a well developed sucking disk (PI. XIV. 

 Fig. 4). Only tridentate and triphyllous pedicellariæ are found. The tridentate ones (PI. XIV. Figs. 2, 

 6, 33) remind somewhat of those in Ph. placenta, especially the small forms are only with difficulty to 

 be distinguished from those; the widenings from the upper end of the apoph\-sis do not reach to the 

 edge of the blade. Tliere is a rather coarse net of meshes in the bottom of the blade, slightly devel- 

 oped in the .small forms, more developed in the larger ones, and in these latter it is set with thorns 

 (PL XIII. Fig. 12.) The length of the head up to 2""", the neck rather short in the large ones; the stalk 

 of the common structure. In the triph^dlous pedicellariæ the cover-plate is rather slighth" developed, 

 with numerous small holes. The edge finely serrate. The primar\- spines on the actinal side cur\-ed, 

 with a large, white hoof. 



Besides the .species of Koehler, Sp. Grininldii, a .species establi.shed by Doderlein (118), Sp. 



