SALENIA VAEISPINA. 21 
mens, and in the older ones there seems to be considerable variation in the 
position of the madreporic body ; so that the position of the madreporic 
genital can certainly not be taken as expressive of any generic value in this 
family, if we are to judge by the recent species. It is not uncommon (five 
specimens) to find two genital plates which carry traces of the madreporic 
body ; and though the right genital is the one which is ir^ost commonly the 
madreporic, yet in the first specimen of this species of Salenia described it 
was the left genital plate which carried the madreporic body. This induced 
Duncan * to refer this species to Peltastes.f 
The crennlation of the tubercles can be traced in the earliest stages ex- 
amined, but its distinctness varies greatly in different individuals. It is quite 
distinct in the large primary tubercles near the abactinal region, it becomes 
indistinct near the ambitus, and at the actinostome the tubercles are smooth. 
The large primary pedicellariiB, both in the ambulacral and interambulacral 
areas, are not numerous. We do not find more than two large, short- 
stemmed, long-headed, slender-pronged pedicellaria^ in each of these areas. 
The others, very numerous, are quite small, short-stemmed, stout-headed 
pedicellaria?. In the ambulacral system these small trifid pedicellarite are 
thickly placed throughout the area ; and in specimens measuring 7 or 8 mm. 
in diameter there are six or seven similar pedicellariae in each of the large 
buccal plates of the actinostome. 
The j)lates of the actinostome are more numerous than in S. Pattersoni, 
and are not as regularly arranged as in that species, in which the acti- 
nal imbricating plates resemble the actinal plates of the CidaridEe, both in 
their regular arrangement and in forming the continuation of the ambu- 
lacral and interambulacral coronal plates on the actinal membrane. In a 
specimen of S. varispina measuring 7 mm. in diameter, there are four or 
five concentric rows of actinal plates between the large buccal plates and 
* Ann. and Mag. of Nat. Hist., XX., 1877. 
t This species is retained in the genus Salenia, although Dr. Duncan has proposed to remove it to 
Peltastes. As I have already stated in the Revision of the Echini, and in the Bulletin of the Museum 
(I., No. 9), when first describing this species, it differs somewhat from Salenia proper, but it does not seem 
to nie to belong to the group of Salenidoe with which Peltastes is associated, in which the suranal plate is 
placed directly opposite one of the genital plates, while in all the recent SalenidiB thus far described 
they at least all agree in having an ocular plate opposed to the median line of the suranal plate, the 
adjoining genital plates uniting just in front of this imaginary median line so as to separate the ocular 
plate more or less from the anal system. (Vide A. Agassiz, Revision of the Echini ; S. Loven, Echino'idees ; 
M. P. Duncan, Ann. and Mag. of Nat. Hist., 1877, 1878; Wyv. Thomson, Voyage of the Challenger; 
A. Agassiz, Echinoidea of the Challenger.) 
