SALEM A VARISPINA. 1.-, 



atagea collected the paira of buccal [dates arc quite distant. In the abactina! 

 system the diii'ereneea due to age arc quite marked. The plates covering 

 the anal opening are lew in number, and comparatively large in the younger 

 stages; with increasing size the plates become inure numeroua and relatively 

 smaller, and carry from <>nc to two minute tubercles. The granulation of 

 tin' genital and ocular plates becomes also more distinct with increasing size, 

 forming more or less regularly radiating lines; the outer edges el' the plates 

 of the genital ring become also somewhat indented, the inner edges of the 

 ocular plates are grooved in the extension of the radiating lines of the gran- 

 ules of these plates. The gills of S. Patlersoni are stouter and less branching 

 than the gills of S. varispina, and the few sphaeridia noticed arc remarkable 

 for their small size and globular outline; one or two sphaaridia are placed in 

 the ambulacra! areas close to the r<\<j;r of the ocular plates. 



Salenia varispina A. Ag. 



This species, of which only a single young specimen had been collected bj Mi. Pourtales, ha 



found from Lai. 24°36' X. Long. 84° 5' W., as far as Granada ami Bai • [.ths of 



334-1,200 fathoms. It is most abundant in depths between 100 and 600 fathom 



For other localitie . see Bull. M. ('. /. . V., No. a, p 186, Ws ; VIII., X... 2, p. 71, 1880. 



PL VI. Figs. l-n. 



How far the obliquity of the axis of the apical system is a structural feature 

 of sufficient importance to he considered a generic difference, it is difficult to 

 decide. In Salenia we undoubtedly have in the asymmetrical arrangement 



of the plates of the apical system a Icat uro somewhat prominent!} developed, 

 which is Found in all Echinoderms, and which is dm' to the original mode of 

 growth of the plates of the embryo Ivhinoilonn in a spiral curve. Traces of 

 this are plainly t<> he seen in the unequal development of the genital and 

 ocular plates throughout the group of Echini, in no one of which do we find 

 the live plates either of the genital or ocular system symmetrically devel- 

 oped, or exactly symmetrically arranged in relation lo a longitudinal axis. 

 We find this in the apical system of the I'alavhiuiihe, the Echinothurise, the 



CidaridsB, the Echinidse, the Clypeastroids, and the Spatangoids, as well as 

 in the asymmetrical test of all young Echinoidea; and perhaps we may tract' 

 the different degree of development of the live series of ambulacra! ami inter- 

 ambulacra! zones throughout the group of Echini to such a primitive differen- 

 tiation. As Neumayr has suggested, tic appearance of the puranal plate mi 

 Salenia may not have the meaning or importance which has been attached to 



