442 



ME. W. P. SLADEN ON THE ASTEEOIDEA 



Three young specimens, two of them being very small. Com- 

 pared with E. caudatum, the abactinal surface slopes at a much 

 smaller angle from the apical pole, whilst the contour of the test, 

 viewed from above, is much more rotund than in similar-sized 

 specimens of the Atlantic species. The intrapetalous fasciole 

 forms a wider triangle outwardly ; and the anal and subanal fas- 

 cioles are disconnected in exam|)les measuring only 7*2 millims. 

 in length ; whilst in E. cordatum of even greater size they are 

 unmistakably confluent. The aj)ical disk is scarcely excentral ; 

 and the peristome, though only slightly so, is more anterior than 

 in the young of E. cordatum. It will be further found, when 

 comparison is made between the two species, that relatively the 

 periproct occupies a very high position on the posterior end in the 

 present form, and also that the zones of the posterior lateral 

 ambulacra converge only very slightly as they approach the am- 

 bitus, whilst in E. cordatum they approximate rapidly. 



An example of this species of the same size as the young E. cor- 

 datum, given by A. Agassiz in the ' E-evision of the Echini,' has 

 been figured for the purpose of comparison {cf. PI. YIII. figs. 14, 

 15, 16, 17). 



ScHiZASTER VE^s^TRicosus, Gray. 



1851. Schizaster ventricosus, Gr«y, Ann. Sf- Mag. Nat. Hist. vol. vii. 

 p. 133. 



Schizaster Jukesii, Gray, ibid. p. 133. 



1855. Schizaster (Nina) ventricosus, Gray, Cat. Rec. Echinida, Brit. 

 Mus. p. 60, t. iv. fig. 2. 



Schizaster (Nina) Jukesii, Gray, ibid. p. 61. 



1872. Schizaster ventricosus, A. Agassiz, Rev. Echin. (III. Cat. Mus. 



Comp. Zool.), p. 158. 

 Coll. St. John: lat. 31° 13' N., long. 136° 73' E., 48 fathoms. 



The collection contains one small specimen of this very fragile 

 Echinoid, and measures only 14 millims. in length. Compared 

 with >S'. canaliferus, the contour, when seen from above, is more 

 elliptical, the test being much fuller and more rotund in the pos- 

 terior portion, and having its greatest breadth across the hinder 

 third ; the apex is not so eccentric ; and the present Schizaster is 

 further characterized by the great height of the posterior portion 

 of the test ; a rapid slope to the actinal surface forms the trun- 

 cate anal end, the upper part of which does not overhang the 

 lower, the periproctal orifice beiog situated very high up on the 

 area. The odd anterior ambulacrum is not so wide as in S. cana- 



