PALuEOTROrUS LOVENI. 



169 



The actinal system varies in outline, but the general system of plating 

 covering it seems to be quite uniform, the number of the larger plates 

 being the same in the three specimens figured Figs. 241. 242, 243 (PI. 

 87, figs, .s', 10, 11). The same is the case with the anal system, Fig. 244 

 (PL 87, fig. 0). 



The ambital plates of the lateral posterior ambulacra extend towards the 

 centre of the plastron, they are enclosed by the subanal fasciule to such 



1 \ 5 V- 



23 mm. 



Fig. 241. I'AL.EciTi'.nrrs Loveni. 



Fig. 242. Pal-eotropus Loveni. 



an extent as almost to join across the median interambulacral plates and 

 leave them but a narrow connecting line (PI. 87, figs. 1, 4). 



Seen in profile (PI. 87, fig. 3) the bare posterior ambulacral plates extend 

 as far as the level of the anal system, but the rest of the test carries the 

 same general tuberculation characteristic of the ambital tract on the actinal 

 side. Seen from above (PI. 87, fig. :.'), it is seen that the tuberculation 

 becomes more distant and less prominent as we approach the apical system, 



Fig. 243. PALiEOTnorrs Loveni. 



23 mm. 



Fig. 244. Pal-eotkopus Loveni. 



and that the abactinal ambulacral plates become greatly reduced in size 

 as they approach the apical system, Fig. 245 (PI. 87, fig. 6"). 



The apical system (PI. 87, figs. 6, 7) closely resembles that of a young 

 Echinocardium figured by Loven. 1 The genital plates are ankylosed, form- 

 ing a single central plate, Figs. 245, 246, pierced by three genital openings, 

 with a small madreporite in the anterior part of the plate. The prominent 



1 Poui-talesia, PI. XVII, fig. 200. 



