86 FOSSIL ECHINI OF THE WEST INDIES. 



Cotteau says that the known specimens from St. Bartholomew are badly 

 worn, but two from the Eocene of Cuba are perfectly preserved and aided 

 in completing his description. Tubercles are of two kinds: The larger, 

 which are crenulate and perforate, occur dorsally near the summit and 

 especially anteriorly on the border of the furrow; they are everywhere 

 very definitely limited by the peripetalous fasciole. The other tubercles 

 are fine, crowded, homogeneous, very small, principally abundant above 

 the ambitus and in the marginal region. The peristome is labiate, semi- 

 lunar, and very excentric anteriorly. Apical disk relatively little developed ; 

 madreporite long, narrow, traversing the whole area [and, as Cotteau shows 

 in a figure, separating the two posterior genitals 1 and 4 and oculars I and V]. 

 There are 4 genital pores, the anterior pair are smaller and nearer together 

 than are the posterior pair. The peripetalous fasciole is sinuous, following 

 very closely the contour of the ambulacral petals; the subanal fasciole 

 is doubtful. 



Height 44 mm., length 128 mm., width 99 mm. These measurements 

 differ very much from Cotteau 's, who says the height is 43 mm., length 

 117 mm., width 105 mm. His measurements were doubtless taken from 

 one of his Cuban specimens, for his published figure was from one of 

 these, as he states. 



The Washington specimen is longer and narrower than Cotteau's 

 measurements and also than his published figure, and the apical disk is 

 much farther forward, being about 32 mm. from the anterior border, 

 whereas in Cotteau's figure it is 41 mm. from the anterior border. I 

 think it is quite probably a distinct species, but it is so worn that sur- 

 face characters are largely eroded away and it therefore seems best 

 to leave it where Cotteau placed it. In position and shape of the 

 ambulacra it agrees well with Cotteau's figure, and it may be merely 

 a variant. In the Washington specimen ambulacra II and IV are at an 

 angle of about 160° to each other, and ambulacra I and V are at an 

 acute angle of about 40° to each other. 



This species is distinct from others known in the genus in its great 

 size, its elongate form, elevated anteriorly and strongly inclined pos- 

 teriorly, its wide and deep anterior furrow, its paired ambulacral petals 

 very long and deep, its small tubercles, and very sinuous peripetalous 

 fasciole. 



Eocene, St. Bartholomew limestone, St. Bartholomew, Guppy collec- 

 tion ex Cleve, cotype, U. S. Nat. Mus. No. 115369. Cotteau also cites 

 specimens from the Eocene of Mantanzas, Cuba, which are cotypes 

 and in his own collection. 



Genus BRISSUS Gray, 1825. 



Type species. — Spatangus brissus Leske, 1778, Add. ad Klein, pp. 

 xx, 182. 



Key to the West Indian Fossil Species of Brissus. 



Width of test 70 per cent of length (more or less) ; periproct not visible from above. . . B. brissus 

 Width of test 55 per cent of length (more or less) ; periproct transversely elongate, 



visible from above B. exiguus 



