190 



PANAMIC DEEP SKA ECHINI. 



In another .specimen there are only two genital pores, Fig. 283, which 

 both encroach upon the sutures not only of the genital, but also of the 

 posterior ocular plates. 



The abactinal system of Aerope fulva varies greatly, Figs. 281-283. The 

 position of the genital pores is by no means fixed, and young apical inter- 



5 



oJ mm. 



Fig. 281. Aerope fulva. 



50 nun ? 



Fro. 282. Aerope fulva. 



ambulacral plates marked x on the figures come within the abactinal system. 

 In another and larger specimen there are but two large genital openings 

 (PI. 62, tig. 2) ; the anterior pair are wanting. The madreporic body occu- 

 pies the anterior parts of the right anterior genital, upon which the right 



posterior genital opening encroaches, as well as upon 

 the right anterior ocular. The left posterior geni- 

 tal pore encroaches upon both the adjoining ocular 

 plates as well as slightly upon the left anterior geni- 

 tal plate. The ocular plates are large, irregularly 

 pentagonal; the odd anterior ocular is more regu- 

 lar in outline and far larger than any of the others 

 (PI. 62, figs. 1-3). 



The pairs of simple pores perforating the abacti- 

 nal ambulacral plates enclosed by the peripetalous 

 fasciole are seen on Plate 62, tigs. 1-3. The spines within the fasciole are 

 slightly curved towards the anterior extremity. Those above the ambitus 

 outside of the fasciole trend towards the posterior extremity, and are fre- 

 quently spathiform, terminating in a hook (PI. 62, figs. 10, 12, 13). The 

 miliary spines are fine, straight, and thickly crowded on both sides of the 

 anterior ambulacral area. On the sides of the test the radioles are some- 



-1n mm. (Fragment |. 



Fig. 283. Aerope fulva. 



