p. H. CAEPENTEE ON CEETACEOUS COMATUL^. 551 



Diameter 5 mm. ; height nearly 2*5 mm. 



Locality. The (Upper) Chalk, Margate. Wetherell Collection, 

 British Museum. 



BemarJcs. The form and regular arrangement of the cirrhus-sockets 

 and the want of plication of the basal grooves distinguish this species 

 from both A. ^aradoxa and A. rugosa. The specimen described is 

 of special interest from the proof which it furnishes of the correctness 

 of Lundgren's explanation * of the so-called ' ambulacra ' of A. jjara- 

 doxa as the grooves in which the basals are lodged. I have much 

 pleasure therefore in naming the species after him. 



3. Antedon steiata, n. sp. (PI. XXIII. fig. 5.) 



The centrodorsal is a roughly circular thick disk with steep sides 

 and a deepish hollow at the dorsal pole, on the sloping wall of which 

 is a faint trace of a stellate impression (fig. 5, c). It bears numerous 

 cirrhus-sockets in four or five irregularly alternating rows, probably 

 about forty in all, if the portion concealed by the matrix be allowed 

 for. They have a circular or oval shape, the largest reaching nearly 

 2 mm. in diameter. Each is a deepish hollow with a very distinctly 

 striated rim, and at or just above the middle a small opening, which 

 is usually somewhat elongated transversely and has slight elevations 

 around its ends (fig. 5, c). These are seen in the best-preserved 

 sockets to be the more prominent parts of a thick articular rim 

 which surrounds the opening of the cirrhus-canal (fig. 5, d^. 



The ventral surface is very flat and rather obscured by the matrix, 

 which occupies the stellate central cavity and conceals the inner ends 

 of the basal grooves. These seem to have been pear-shaped, and 

 their sides show no indications of plaiting, which, had it existed, 

 would have been preserved like the striae of the cirrhus-sockets. 



Diameter nearly 9 mm. ; height 4| mm. 



Locality. The (Tipper) Chalk, Dover. British-Museum Collec- 

 tion. 



Bemarl^s. This species has a considerable superficial resemblance 

 to A. rugosa^ but its centrodorsal is rather higher and bears more 

 cirrhi, the sockets of which are quite diff'erent from those of that type. 

 They are more like those of A. Lundgreni, but are arranged quite 

 difi'erently and are far more distinctly striated. In A. phalangium 

 of the Mediterranean the margins of the cirrhus-sockets are quite 

 plain ; but the articular rim around the opening of the axial canal 

 has very much the same shape that it has in A. striata. 



4. AifTEDON- laticieea, u. sp. (PL XXIII. fig. 6.) 



The centrodorsal is roughly hemispherical with a pentagonal 

 outline, and bears eight cirrhus-sockets in a single incomplete row 



'^ "Om en Comaster och enAptpchus fran Kopinge," Ofversigt af KongL 

 Vetenskaps-Akademiens rorhandliugar, 1874, p. 65. 



