ECHINOIDEA. 1. 



71 



involuted, only the point is somewhat widened, and the edge of this terminal jDart is almost straight 

 cut off, but irregularly serrate. The involuted part of tlie blade is filled by an irregular net of meshes. 

 In the smaller form of tridentate pedicellarise (PI. XIII. Figs. 17 — 18) there is a comparatively larger 

 widened part in the point of the blade, and a corresponding smaller, involuted part; this feature is 

 rather varying according to the size. The edge of the widened part is also here irregularly serrate, 

 but may in the smallest specimens be almost quite straight and regularly serrate. The blade is less 

 curved in the small form than in the large one, and accordingly the valves are less wide apart when 

 the pedicellaria is shut, which feature is excellently seen in the figures of Wy v. Thomson. I quite 

 agree with Wyv. Thomson, when he thinks this smaller form to be <a modification of the first 

 more or less reduced in size and lengthened in its proportions-; on the other hand I must protest 

 against his finding it like some of the common varieties in the Cidaridse ■ (op. cit. p. 739). Any resem- 

 blance to the pedicellarise of the Cidarids is absolutely not foinid, except so far that both forms are 

 pedicellariae , and as such agree in their chief structures. — The size of the tridentate pedicellarise 

 (the head) is up to r2""", as stated by Wyv. Thomson. The neck is rather short in the large pedi- 

 cellarise, somewhat more developed in the small ones. The triphyllous pedicellarise have a very large 

 cover-plate, most frequently almost without holes; only in the median line there is a series of large 

 holes, made by protuberances from the sides of the cover-i^late growing towards the middle and coa- 

 lescing there (PI. XII. Fig. 34). The outer edge is rather strongly dentate. The stalk of the pedicel- 

 larise is of the structure common in the Echinothurids, irregularly perforated. The sphseridise are rather 

 long-stalked, their head beautifully round and smooth (PI. XIV. Fig. 13). 



The spicules are arranged in two series in the lower part of the tube feet; they are here 

 narrow, more or less rod-shaped, with few, sometimes no holes (PI. XI. Fig. 29); they are placed across 

 the longitudinal axis of the foot. Above the\- are large, irregular fenestrated plates quite encompassing 

 the foot. 



The longitudinal muscles > are well developed; on the other hand no distinct organs of 

 Stewart were seen in the specimen I opened. To be sure , K o e h 1 e r (op. cit.) states the organs of 

 Stewart to be well developed. As Koehler, however, follows Bell in regarding Calveria hystrix and 

 fejicstrata as synonyms, it cannot be seen, which of these species he has examined. Nor could I see 

 the organs of Stewart in a specimen of the latter species. 



Of Calveria Iiystrix two specimens have been obtained by the <Ingolf -Expedition on the sta- 

 tions 89 (64° 45' N. Lat., 27° 20' W. L. 310 fathoms, the bottom mud, bottom temperature 8"), and 97 

 (65° 28' N. Lat., 27° 39' W. L. 450 fathoms. Sandy mud. Bottom temperature 5" i). The specimen from 

 St. 97 is very beautifulh- preserved, and as the colour has almost not faded — to judge by a coloured 

 sketch made on board from the living animal — it is here figured in colours (PI. III. Figs. 1—2); only 

 the darker bands mentioned by Wyv. Thomson (p. 740), are no longer seen distinctly; in the original 

 sketch they are indicated. 



Whether the specimen of 3"'"' mentioned by Agassiz in Rev. of Echini, Pt. II. p. 273, really is 

 a C. hystrix, cannot be seen from the figures. Agassiz, to be sure, says that the pedicellarise are 

 similar ; but it is not quite evident whether they resemble those of C. hystrix, or those of Asthcnosoma 

 Grubei; and even if the meaning be that they resemble the figures of the pedicellarise in C. hystrix 



