ECHINOIDEA. I. 71 



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

 cut off, but irregularly serrate. The involuted part of the 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 Wyv. 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 dike some of the common varieties in the Cidaridse (op. cit. p. 739). Any resem- 

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

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

 (the head) is up to i-2 mm , 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-plate 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 (PL 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 they 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 



fenestrata 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 hystrix 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 beautifully 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, i 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 min mentioned by Agassiz in Rev. of Echini, PL 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 Asthenosoma 

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



