194 PANAMIC DEEP SEA ECHINI. 



Station 3355, off Point Mala, 182 fathoms. Lat. 7' 12' 20" N. ; Long. S(T 

 55' W. Bottom temperature, 54 .1. Bk. glob. sh. 



Station 3357, southwest of Mariato Point, 782 fathoms. Lat. 6° 35' N. ; 

 Long. 81 44' W. Bottom temperature, 38 .5. Modern green sand. 



Bathymetrical range, 182-782 fathoms. Temperature range, 54M- 

 38".5. 



Aerope Wyv. Thom. 

 Aerope fulva A. Ag. 



Aerope fulva A. Ag., Bull. M. C. Z. 1898, XXX II, No. 5, p. 81, Plate VIII, figs. 5, 6. 



Plates 55, figs. 6-8; 61; 62. 



This species is readily distinguished from A. rostrata Wyv. Thorn. 1 by its 

 proportionally greater length compared to its width, the lateral flattening 

 of the test, and the pointed anal rostrum (Pis. 55, figs. 6-8; 61, figs. 1- ). 

 It has more the outline of the larger specimen figured on PI. XXXIII. figs. 

 1-5 of the " Challenger " Echinoidea, which is of the same size as that here 

 figured (PI. 55, figs. 6-8). The differences in outline of the specimen figured 

 on PI. XXXIII. of the "Challenger" Echinoidea are, however, all compati- 

 ble with differences due to age. The primary tuberculation is most uniform 

 over the test, within the peripetalous fasciole, and over the actinal floor, 

 excepting the bare ambulacra; it is also much closer (Pis. 61, figs. 1-3; 62, 

 figs. 6-8) than in the species described by Thomson ; the primary radioles 

 are quite slender (PI. 62, figs. 10-12) compared with the stouter radioles of 

 A. rostraia? 



The vertex of Aerope fulva is at the apical system, well anterior of the 

 peripetalous fasciole (PI. 61, fig. 3), while in the " Challenger" species, even 

 in the larger specimens, the vertex is at the abactinal pole of the peripetal- 

 ous fasciole in a position far posterior to that it occupies in A. fulva. The 

 posterior extremity of A. fulva also tends to turn up somewhat snout-shaped 

 for the reception of the anal system (PI. 61, fig. S), while the posterior 

 extremity of A. roslrata slopes quite gradually to meet the rounded anal 

 extremity. 



The actinal plastron is elongate, triangular, consisting of two plates ; it 

 is closely packed with primaries, specially near the posterior edge (PI. 61, 



1 " Challenger" Echinoidea, Pis. XXXIIf, figs. 8-12; XXXIII s , figs. 8, 9. 

 » "Challenger" Echinoidea, PI. XXXIII, figs. 1-3. 



