128 Bulletin, Vanderbilt Marine Museum, Vol. IV 



the West Indies, the Gulf of Mexico, and the northern coast of South 

 America, as far down as Abrolhos Islands, Brazil. 



Material examined: Six specimens dredged in shallow water, 

 Egg Island, Bahamas, British West Indies, January 19, 1925, by the 

 "Ara," Cat. no. 230. One specimen, from the same locality, Cat. no. 

 271 ; photographed. Two specimens from south of Catalina Creek, 

 Cuba, 5 fms., February 11, 1924, Cat. no. 261. 



Color: This, the "pencil urchin" of the West Indies, is chocolate- 

 brown, marbled with white or cream color ; there are frequently 

 touches of red, especially on the spines. Full-grown specimens with 

 a test diameter of 60 mm. have been recorded by Dr. H. L. Clark. 

 The present writer has records of some taken at Miami, Florida, 

 1923, with a test diameter of 71, 73 and 75 mm., respectively, with 

 primary spines 46, 44 and 48 mm. long. 



Habits : Unrecorded. 



Development: Not exhaustively studied. 



Technical description : Test thick, circular, turban-shaped with 

 the actinal and abactinal regions similarly flattened. The genital 

 plates are nearly rectangular; the ocular plates are somewhat trian- 

 gular with somewhat rounded sides. The anal system is pentagonal; 

 the larger plates adjoining the genital plates extend a short distance 

 towards the ocular plates, separating the genital plates but very little. 

 The genital openings are placed near the outer margins of the plates. 

 The entire abactinal system is covered with miliary tubercles of 

 approximately equal size which bear small, blunt, laterally flattened 

 secondary spines. The ambulacral region has one outer row of miliary 

 tubercles separating it from the poriferous zone and four rows of 

 smaller miliary tubercles, two rows of which are well defined and 

 extend between them almost the full length of the ambulacra, while 

 the other two rows are very irregular and are composed of still 

 smaller tubercles. The two principal rows of interambulacral tuber- 

 cles are separated by a wide median row of miliaries of almost equal 

 size, the miliaries on the median line being a little smaller, while those 

 around the scrobicular circle are very little larger. The mamelon is 

 small. 



The primary spines are cylindrical, slightly tapering distally, of 

 moderate diameter. The convex lateral surface of each primary has 

 a roughened, fluted appearance, caused by rather regular, coarse, 

 rounded tubercles or granules, arranged in longitudinal series; these 



