132 PANAMIC DEEP SEA ECHINI. 



posterior lateral interarabulacra from those of the trivium. There are the 

 two posterior ocular plates, and the anterior ones are ankylosed, the oculars 

 of the trivium being lost and occupied by the madreporite. (Pis. 67, fig. 2- 

 69, figs. 3, 4.) 



No Pourtalesia has the marginal fasciole of Sternopatagus. It has the 

 labium and sternum of Plexechinus separated by the posterior lateral inter- 

 ambulacra, although the actinal plate of the left posterior interambulacrum 

 cannot be traced in M. de Meijere's figure, and the structure of the odd 

 interambulacrum is entirely different from that of any Pourtalesia. M. de 

 Meijere considers Sternopatagus^ an intermediate form between Ananchy- 

 tidae and the Pourtalesiae. It looks to me far more Ananchytid than 

 Pourtalesian. 



Pourtalesia A. Ag. 

 Pourtalesia Tanneri A. Ag. 



Pourtaleaia Tanneri A. Ag., Bull. M. C. Z. 1898, XXXII, Ko. 5, p. 77 ; PL VIII, figs. 1, 2. 



Plates B, fig. ^ ; 55, figs, i, ^ ; 56 ; 57. 



This species (PI. 55, figs. 1, 2) is closely allied to P. laguncula A. Ag.^ 

 It differs from it in the shape of the test, which is more elongate (PI. 56, 

 fig. 1), less bottle-shaped, more like the younger specimens of P. laguncula 

 A. Ag.,^ and consequent greater length of the coronal plates, especially 

 in the left posterior ambulacral and interambulacral areas; compare* 

 Chall. Ech. PI. XXII % figs. 7, 9 with PI. 56, figs. 1, 3; the anterior ex- 

 tremity of the test is higher (PI. 56, fig. 4) ; the larger primary tuber- 

 cles are concentrated on the sides of the test in a triangular space 

 (PL 56, figs. ^, 3j extending from the anal system to the junction of the 

 ambitus with the anterior edge of the posterior ambulacra. The primary 

 radioles on the flanks of the test are also longer, while in P. laguncula and 

 P. miranda they are somewhat spathiform. 



1 1 am blamed by M. de Meijere for not putting on one plate the figures belonging to one 

 species. We do not find in M. de Meijere's Report any greater concentration of figures belonging 

 to one species than is tlie natural result of one's inability to put a gallon into a pint measure. I 

 would refer to the position of M. de Meijere's figures of Sternopatagus on three widely separated 

 plates, of Sternopneustes on the same number, and others, which do not seem to show that regard for 

 the reader the lack of which is so blameworthy in others. 



« "Challenger" Echinoidea, p. 137, Pis. XXII », figs. 7-9; XXXI, figs. 1-11. 



« "Challenger" Echinoidea, PI. XXXI, figs. 10, 11. 



* See also Lovdn, Pourtalesia, PI. VI, figs. 37, 38. 



