MEOMA. 603 



Caledonia, in the possession of M. Crosse, and a smaller lot of specimens of 

 different sizes in the Stuttgard Museum, have satisfied me of the identity 

 of the species here united ; I can consider them only as differences due 

 to growth. 



Sandwich Islands ; Society Islands ; East India Islands ; Australia ; Red Sea. 



(BRISSUS.) Meoma. 



Meoma Gray, 1851, Ann. Mag. N. H. 

 (See Part II. p. 358.) 



Meoma grandis 



! Meoma grandis Gray, 1851, Ann. Mag. N. H., VII. p. 132. 



PI XX VI. f. 28-38; PL XXXIV f. 1, 2. 



Test more flattened or arched than in the somewhat conical M. ventricosa ; 

 readily distinguished by its coarser and more distant tuberculatum, both 

 within and without the peripetalous fasciole on the abactinal side, the deeper 

 anterior groove at the ambitus, its less angular peripetalous fasciole, espe- 

 cially in the posterior interambulacrum. The ridge separating the pairs of 

 pores carries but few large miliaries at the outer edge of the poriferous zone ; 

 while in M. ventricosa this line is formed of closely packed small miliary 

 tubercles, extending to the median interporiferous space. The principal dif- 

 ferences to be noticed on the actinal side are the shorter actinal plastron, 

 and the anteriorly curved subanal fasciole, which crosses the actinal plastron 

 in a straight line in M. ventricosa. The great size and distant tuberculatum 

 of the actinal surface, as well as the comparatively broad ambulacral avenues, 

 readily distinguish the Pacific from the West Indian species. The spines are 

 quite short, stout, very slightly curved. The color, when alive, is a dark 

 chocolate-brown. This species lives buried in the sand at a depth of from 

 two to three fathoms. 



Acapulco ; Gulf of California. 



Meoma ventricosa 



! Spatangus ventricosus Lamk. 1816, An. s. Vert., p. 29. 

 ! Meoma ventricosa Lutic, 18G4, Bid., p. 120. 

 (See Part II. p. 358.) 



PI. XX. f. s; PI. XXII. f. s, 4; PI. XXVI. f. 31-34; PL XXXVIII. f. 24, 25. 



Florida ; West India Islands. 



