SYSTEMATIC DESCRIPTIONS SPATANGINA. 75 



Key to the West Indian Fossil Species of Parastcr. 



A. Test about as wide as long; apical system central or a little posterior. 



B. Ambulacrum III scarcely depressed at ambitus; petals II and IV nearly straight, 



very widely diverging P. anlillarum 



BE. Ambulacrum III much depressed at ambitus; petals II and IV slightly curved; 



not so widely diverging. 



C. Petals II and IV curved outward at tip somewhat abruptly; petals I and V 

 three-fourths as long as II and IV, narrow and somewhat 



pointed P. Parkinson i 



CC. Petals II and IV not curved outward at tip; petals I and V not much more 



than half as long as II and IV, wide and rounded. 



D. Interambulacra 1, 4, and 5 near apical system, much elevated and some- 

 what compressed; petals widest near or just distal to middle, taper- 

 ing more or less towards each end; test rounded pentagonal P. clevei 



DD. Interambulacra 1, 4, and 5 not much elevated or compressed; petals 



widest near tip; test more evenly oval P. loveni 



AA. Test not nearly as wide as long; apical system markedly posterior P. subcylindricus 



Paraster antillarum (Cotteau). 

 (Plate 13, Figures 1 to 3.) 



Schizaster anlillarum Cotteau, 1875, Kongl. Sven. Vet. Akad. Handl., vol. 13, No. 6, p. 28. 



plate 5, figs. 3 to 5. 

 Schizaster subcylindricus Guppy (pars), 1882, Scientific Assoc. Trinidad, Proc., part 12, p. 197. 



The following is an extract from the original description of this species: 



Species of medium size, nearly as wide as long, subcordiform, expanded 

 anteriorly and acuminate posteriorly. Upper face swollen, sloping ante- 

 riorly, having its greatest height a little posterior to the apical disk. The 

 posterior face is narrow, subangular, obliquely truncate. Lower face 

 slightly swollen, rounded on the borders, sub-depressed anterior to the 

 peristome. Apical disk subcentral, a little posterior. Anterior furrow 

 wide, deep dorsally and attenuated toward the ambitus. Anterior am- 

 bulacrum III narrow, elongate, and straight, with simple pores in pairs. 

 The paired ambulacra are petaloid, subflexuous, excavated, closed at the 

 ends and unequal. The anterior ambulacra II and IV are longer than the 

 posterior pair; poriferous areas with pores which are alike elongate and 

 narrow, united by a furrow; interporiferous areas narrower than the por- 

 iferous. Interambulacra are narrow, compressed, and prominent near the 

 apex. The peristome is semicircular, near the anterior border. Periproct 

 oval, situated in the posterior face. Peripetalous and subanal fascicles 

 are indistinct, yet visible enough to show they are like those of Schizaster. 



There is only one specimen in the collection in Washington, which 

 measures 20.5 mm. in height, 28 mm. in length, and 27.5 mm. in width. 

 These measurements greatly exceed Cotteau's, for he says 11 mm. in 

 height, 17 mm. in length, and 16 mm. in width. However, he mentions 

 having 2 specimens, both badly preserved, and his measurements were 

 doubtless taken from the other specimen, which I can not locate. It is 

 probable that Cotteau's figures were also taken from this second speci- 

 men mentioned, as the one in hand does not show some of the features he 

 depicts. The periproct is in the upper part of the posterior face, as 

 Cotteau describes it, but is indistinct, so does not come out well in the 

 photograph of the posterior view. The specimen is so much worn that 

 it shows very little of structural detail. This species (antillarum) differs 

 from clevei in the shape of the test and the shape and depth of the anterior 



