SYSTEMATIC DESCRIPTIONS — SPATANGINA. 95 



angles to the long axis, lying at an angle of about 160° to each other. The 

 posterior pair I and V converge strongly, forming an acute angle of about 

 65 posteriorly. Poriferous areas are narrow, the outer pores elongate, 

 oblique; the inner slightly oval. The interporiferous areas are narrow; near 

 the peristome the pores are close together and situated near the lower border 

 of each plate. Interambulacra are broad, the lower border of the plates 

 being markedly curved. Plastron long, rather narrow, and it, with the 

 adjacent ambulacra I and V, is moderately but distinctly elevated. 

 The primary tubercles are small, perforate, crenulate, and scrobiculate ; 

 scattered on the dorsal surface, more crowded toward the ambitus and 

 ventrally. Small granules are scattered abundantly between the primary 

 tubercles and form rings around the latter. A few spines are preserved in 

 protected spots; these spines are slender and acicular, and the best pre- 

 served measure about 5 mm. in length. The apical disk is very small, 

 with 4 genital plates having extra large genital pores; the pores of genitals 

 2 and 3 are nearer together than are those of 1 and 4. The madreporite 

 extends back, separating the posterior genitals and oculars. Oculars are 

 very small. The peristome is situated anteriorly, but at a considerable 

 distance (30 mm.) from the anterior border; it is in a moderate depression, 

 transversely elongate, labiate. The periproct is not clearly outlined in any 

 of the specimens, but it is large, oval in the vertical plane, and situated on . 

 the posterior face, not visible from above. 



This species is represented by several finely preserved specimens. 

 The holotype (plate 17, fig. 1), which is the most complete dorsally, 

 measures about 43 mm. in height, 119 mm. in length, and 108 mm. in 

 width across ambulacra II and IV, which is the widest part of the test. 

 The paratype (plate 16, fig. 8), which is a little smaller than the holotype, 

 measures 41 mm. in height, 110 mm. in length, and 100 mm. in width. 

 It is extremely well preserved ventrally and in part dorsally. 



The two described specimens are light gray. A third individual from 

 the same locality but from yellowish shales, which color the specimen has, 

 is referred to this species with some doubt. It is well preserved, but is 

 very imperfect dorsally. It has the same form in outline as the type, but 

 is very much flattened. The plastron is much narrower anteriorly and 

 wider posteriorly. My impression is that it belongs to a distinct and 

 new species, but it has not sufficient structure preserved for a proper 

 description. It is interesting that some spines are associated with speci- 

 mens of this species. This is the only species of West Indian fossil Echini, 

 other than the species of Cidaris, of which I have seen the spines, and 

 they have not been reported in any other species as far as known. The 

 large size, conical form, and the great width anteriorly and narrowness 

 posteriorly distinguish this species from any other West Indian or 

 American species of the genus. 



Oligocene, high bluff, 2 km. southwest of Juana Diaz, Porto Rico, 

 from huge block of limestone, halfway up slope and just beneath basal 

 limestone ledge, in situ, 1 specimen, the holotype, station 196, American 

 Mus. Nat. Hist. No. 18574. High bluff, 2 km. southwest of Juana Diaz, 

 Porto Rico, greenish to yellowish shales (Juana Diaz), exposed in the west 



