Boone, Echinodermata, Cruises of "Eagle" and "Ara," 1921-28 149 



Moira atropus A. Agassiz, Mem. Mus. Comp. Zool., Rev. Echini, vol. 

 Ill, part I, p. 146, 1872 ; ibid, part II, p. 146 ; ibid, part III, p. 

 365, pi. 23. 



Family: SPATANGIDAE. 



Subfamily: Brissina. 



Genus: MEOMA Gray. 



Meoma ventricosa (Lamarck). 



Plates 95 and 96. 



Type: Lamarck's type came from "l'ocean des Antilles." It is 

 deposited in the Paris Museum. 



Distkibution : Recent: Littoral to 240 fms. "West Indian region. 

 Fossil: Recorded from the Tertiary of Cuba and the West Indies by 

 Agassiz. 



Material examined: One large specimen, dredged at Egg Island, 

 British West Indies, January 19, 1925, by the "Ara." 



Color: Yellowish brown or reddish brown. 



Technical description: Urchin large, specimens attaining a long 

 diameter of 188 mm. having been recorded. The test is thick, broadly 

 elliptical, somewhat heart-shaped from above. The actinal surface is 

 flat, except the projecting posterior lip of the actinostome. The anal 

 extremity is truncated obliquely towards the sloping actinal surface; 

 regularly arched from the edge of the test to the apex, which latter is 

 anterior, almost corresponding with the abactinal center; regularly 

 arched from anal and anterior extremity to apex, lateral ambulacra 

 deeply sunken, with the posterior pair distinctly longer than the ante- 

 rior pair which diverges at a much greater angle from the very shal- 

 lowly defined odd, or fifth, ambulacrum, which is situated in a very 

 lightly marked anterior groove. The peripetalous fasciole is of 

 uniform breadth, clearly defined, the four genital openings diverging 

 posteriorly. On the interambulacral plates, enclosed by the fasciole, 

 the tubercles are arranged in single rows parallel to the suture; the 

 remainder of the test is covered by closely crowded tubercles of uni- 

 form size, supporting short, sharp spines. On the actinal region of 

 the test the tubercles are larger immediately adjacent to the ambu- 

 lacra, diminishing in size towards the edge and towards the central 

 part of the actinal plastron. This actinal plastron is bottle-shaped, 

 short-necked near the actinostome, with a very faint keel near the 

 central part, and bounded posteriorly by the narrow, usually open, 

 subanal fasciole, the anal extremity of which is bent near the base of 



