34 PANAMIC DEEP SKA ECHINI. 



in each interambulacral area, except in the right, posterior, interambulacral 



area, where a small fifth plate had developed. In our specimen, measuring 

 26 mm. in diameter, the aetinal system is 9 mm. in diameter. Fig. 17. The 

 arrangement of the small secondary tubercles on the buccal plates is shown 

 on PL 5, fig. 1 ; these are few in number and are limited to the aetinal 

 side of the plates. 



The abactinal system is 8.5 mm. in greatest diameter (PI. 5, fig. .')• It 

 is nearly bare of miliaries; these are widely separated and arranged along 

 the edges of the genital plates, with two or three in the centre of the plates 

 and round the genital pores. Along the distal side of the ocular plates 

 extends one line of secondaries and miliaries. 



The madreporic body is well developed in the central part of the genital 

 plate. The anal plates, like the other plates of the abactinal system, are 

 bare, with from one to three miliaries on each anal plate. The arrangement 

 of the older plates of the anal system is quite regular (PI. 5, fig. ,.'). The 

 oldest plates occupy the angles of the pentagonal anal system. 



The genital plates are elongate with concave sides flanking the oculars, 

 which nearly join the anal system, and with convex sides against the inter- 

 ambulacral plates. 



When alive the bare spaces of the median interambulacral area are of a 

 deep brownish violet (PI. 14, figs. J, 2), the primary radioles are reddish, 

 the secondary and miliary spines greenish with brownish longitudinal bands. 

 The sutures between the genital and ocular plates, as well as in the anal 

 system, are marked by a sharp violet line (PI. 14, fig. ..'). 



Station 3369, off Cocos Island, 52 fathoms. Lat, 5 32' 45" N. ; Long. 

 86° 55' 20" YV. Bottom temperature 62 .2'. Nullipore and rocky. 



SALENID-S! Agass. 



The discovery of a number of new species of Salenia by the " Challenger " 

 and "Blake" has somewhat modified our ideas of the relationship of the 

 genus to the Cidaridae. The study of the additional species collected by 

 the "Albatross" in 1891 has only emphasized the view of Duncan 1 and 

 Sladen 2 and of Doederlein :i of their relationship to the Echinidse. Although 

 the simple structure of the ambulacra, the solid genital and ocular plates, 



1 Ann. and Mag. X. H., 1877. Ser. 4. Vol. XX. p. 70. 

 - Ann. and Mag. N. II., 1887. Ser. 5, Vol. XIX, p. 132. 

 8 Japanische Seeigel, p. 53. 



