58 PANAMIC DEEP SEA ECHINI. 



found many small pedicellariae somewhat similar to those of the apical 

 system. Each coronal plate also carries from four to six large tridentate 

 pedicellariae. 



In the figures of the auricles (PI. 23, figs. 5, G) a faint horizontal line 

 divides the auricle into two plates, one of which is probably the primordial 

 plate, Figs. 88, 89. 



Station 3382, southeast of Mariato Point, 1793 fathoms. Lat. 6 21' N.J 

 Long. 80° 41' W. Bott. temp. 35 .8. Gn. M. 



ASPIDODIADEMATID.ffi Duncan. 



Dermatodiadema A. Ag. 



Dermatodiadema A. Ag., Pull. M. C. Z. 1808, XXXII, No. 5, p. 76. 



This genus holds to Aspidodiadema the same relation which Echinothrix 

 holds to Diadema. It differs from it in having only small secondary 

 tubercles and miliaries in the ambulacral areas, Fig. 93, as in Cidaris, while 

 in Aspidodiadema the ambulacral plates of" the actinal region carry large 

 primary tubercles, as in Hemicidaris; in D. globulosxuii there are also in 

 addition to the miliaries distant small secondary tubercles, but they have 

 not the Hemicidaris arrangement. 



Two species of the genus have been dredged in the Panamic area. 

 Their representative in the "West Indian area is Aspidodiadema antiMarum 

 collected by the " Blake," which should be referred to Dermatodiadema, it 

 having the miliary and secondary ambulacral tubercles on the actinal plates 

 as in that genus. A. Jacobt/i l and A. tonsum 2 are characteristic Aspidodia- 

 dematidae, while A. microtuberculatum 3 as well as A. antiMarum * are to be 

 referred to Dermatodiadema. 



I did not find in either species of Dermatodiadema the sheathed pedicel- 

 larire so characteristic of the West Indian species. 



In the genital ring of Aspidodiadema and Dermatodiadema the oculars 

 not only all reach the anal system, but they are of nearly uniform size with 

 the genitals. We find in Centrostephanus a very similar genital ring, 



1 " Blake " Echini, PI. IX a , tigs. 3, 7, 10, 15, 18. 



2 "Challenger" Echinoidea, PI. VIIT, tigs. 5, 9. 



8 "Challenger" Echinoidea, PI. VIII, figs. 11, 12, 1G. 

 * " Blake " Echini, PL IX, figs. 3, 4. fi. R. 



