136 



PAXAMIC DEEP SEA ECHINI. 



anterior interambulacra are larger (PI. 57, fig. 5). In this respect P. Tanneri 

 is more closely allied to P. carinata, Fig. 197, in which, according to Loven/ 

 the primordial plates of the posterior interambulacra and the labium occupy 

 much the same position they do in P. Tanneri. A similar arrangement is 

 found in P. ceratopjga and E. cuneata? 



IG mm. 



Fig. 190. Pourtalesia Tanneri. 



Fig. 197. P. carixata. 



After Lovkn. 



The actinal system of P. Tanneri, Fig. 176, is circular (Pis. 56, fig. 4 ; 

 57, figs. ^, 3) ; the outer belt is covered by delicate elongated plates forming 

 three or four irregularly concentric rows. The central part of the actinal 

 system is bare. The course of the odd anterior ambulacrum (Pis. 56, figs. 



Fig. 198. Poukiai.ijsia Jeffrkysi. 

 Ama Lov6n. 



la' 1 ' « V 



10 mm. 



Fig. 199. P. Taxxebi. 



7-^; 57, fig. 2) is Specially well seen from the interior view of the test 

 (PI. 57, fig. -'), which shows tlie rapid widening and arching of the ambu- 

 lacral plates to form the deep nntorior actin.al ambulacral groove. The 



» IxDVon. Pourtale.si.i, PI. VI. fi-s. ■li.-U. ^ i,i., i>i. yn. figs. 48, W. 



