56 



ECHINOIDEA. I. 



cellariæ is fouiid, the large and small ones beiiig upon tlie whole coiistructed in tlie same way. They 

 are finely serrate in the edge. Tlie neck long, the stalk of the common strnctnre. Tlie length of the 

 head np to 1-5""". The triphyllons pedicellariæ of a very fine form, witli well-developed cover-plate, 

 withont holes (always?), and the edge beautifnlly serrate (PI. XII. Fig. 14). — The spicules are in the 

 lower part of the tube foot alniost rod-shaped, with a few holes in tlie middle (PI. XL Fig. 19); they 

 are placed in two series, across the longitudinal axis of the foot. In the upper part of the tube foot 

 they are larger fenestrated piates; the sucking disk well developed. The tube feet in three series, 

 beautifnlly trigeminate as in an Ec/iiinis. The primary spines on the actinal side curved, with a rather 

 long hoof almost not thicker than the spine. Besides the characters mentioned liere, tliere seem to be 

 fouiid good characters in the strnctnre of the test and in the apical area; with regard to tliese char- 

 acters the reader is referred to the description by Agassiz. It is evident tliat this species caiinot 

 be referred to any of the other genera; especially characteristic are the globiferous pedicellariæ, to 

 wliicli nothing correspondiiig is knowii in other Echinothurids. It must form a separate genus, for 

 which I propose the name of Hapalosoma"). 



Of the species that have been referred to Asfhcnosoiiia, the two species A. lougispinuiii and 

 lijaiuai' from Japan described bv Yoshiwara (448), are still left to be mentioned. Of these nothing 

 can for the present be said with certainty; A. longtspinu/u , however, seems to be a Calveria or an 

 Aræosoiiia. 



Plipruinsonia tcmic A. Ag. (A specimen from Challenger st. 237 examined). The tube feet are 

 placed very close together, forming only oiie almost regular series. The spicules highly de\-eloped, 

 irregular fenestrated piates. There is 110 distiiict sucking disk, only some irregular, .slightly branched 

 or unbranched continuations passing from the outermost fenestrated piates of the foot into its point. 

 The primary spines 011 the actinal side endiiig in a little hoof. Only tridentate and triphyllons pedi- 

 cellariæ are found. Of tridentate pedicellariæ a larger and a smaller form are found. The larger form 

 (of which a rather good figure is found in Chall. Ech. PI. XLII. Fi.g- /, and PI. XLIV. Fig. 19) has a 

 ratlier ricli, coarse net of nieshes in the lower part of the blade, and the upper end of the apophysis 

 continues somewhat into the blade as a serrate crest (PI. XII. Fig. 35). This crest is not distinctly seen 

 in the figure in Chall. Ech. (PI. XLIV. Fig. 19), possibly it niay not be a constant feature. The length 

 of the head up to 2-8""". The smaller form (the head up to i™'") reminds niuch of those u\ Ph. p/acnifa, 

 but the contour is somewhat different, and the widenings from the upper end of the apophysis reacli 

 to the edge of the blade (PI. XII. Fig. 40). The neck is long, also in the larger form, the stalk of the 

 common strnctnre. The triphyllons pedicellariæ have a well developed cover-plate; the edge finely 

 serrate. — I have not found the peculiar two-valved, bottle-sliaped pedicellaria figured by Agassiz 

 (Chall. Ech. PL XLIV. Fig. 21). As it is two-valved, it may be taken to be an abnormity. It is, no 

 doubt, a modification of the triphyllons pedicellariæ. This I also take to be the opinion of A g a s s iz 

 when lie says (op. cit. p. 82), that perhaps it is only a modification of < the remarkable long-pronged 

 pedicellariæ figured by Thomson as characteristic of the group»^). — In the description of this species 



') d-Kah'ig — soft. 



2) A few lines lower down in the same paragraph Agassiz seenis to derive this fonn from the tridentate pedicel- 

 lariæ (see above p. 46). 



