500 TOXOPNEUSTES VARIEGATUS. 



Boletia pileolus, to point to its identity with T. semituberculatus rather than 

 to its affinity to (B. rosea) T. pileolus, the young of which has a nearly 

 hare buccal membrane. The material for a definite conclusion is not in our 

 collections, and no positive results can he reached at present. 



Toxopneustes variegatus 



! Echinus variegatus (Lamk.). 181G, An. s. Vert. 

 ! Toxopm ustes variegatus A. Ac, 1872, Rev. Ech., I't. I. p. 1C8. 

 (See Tart II. p. "JUS.) 



PL H. f. 5-6; PL IV. f. 4-5; PI. VI f. 2s; PI VII. f. 7-22; 



PL XXV. f. 17-19. 

 Brazil ; West India Islands ; Bermudas ; South Carolina. 



HIPPONOE. 



Hipponoe Gray, 1840, Svnops. Cont. Brit. Mus. 

 (Sec Part II. p. 301.) 



Hipponoe depressa 



! Tripneustes depressus A. Ac... 18fi3, Bull. M. C. Z, I. 

 I Hipponoe depressa A. Ac 1872. Rev. Ech, l't. I. p. 134. 



The differences between the two species of Hipponoe found on the Atlantic 

 and Pacific sides of the Isthmus of Panama are slight, but well marked. 

 They consist, in the Pacific species, in the comparatively higher coronal 

 plates, the irregular arrangement of the primary tubercles, not forming, as 

 in the West India species, regular vertical rows as well as horizontal ones. 

 There is only one well-defined vertical row of primaries, somewhat nearer the 

 poriferous zone than to the median line in the interambulacral space. The 

 anal system and the actinostome arc comparatively smaller in the Wot 

 India species, in which the buccal membrane is nearly smooth, while it is 

 thickly covered by large plates at its junction with the test in the Pacific 

 species. 



No. of Abartinal Anal Actinal Width 



Coron. I'latcs. Diameter. Height. System. SyBtem. System. Porif. Zone. Spines. 



40. 127. 62. 1G.8 9. 29. 9.8 14. 



118. 71. 



Gulf of California. 



