BARBADOS-ANTIGUA REPORTS 105 



Cidaris tribuloides A. Agassiz, 1872. Rev. Eeh., p. 253; pi. Id 

 and pi. II, figs. 1-3. 



Eucidaris tribidoides Doderlein, 1887. Jap. Seeigel, p. 42. 



There are three specimens of this well-known sea-urchin at 

 hand; one, 38 mm. in diameter with primary spines 35-38 mm. 

 long, from Falmouth Harbor, Antigua ; one 25 mm. with spines 

 of about that length, from Carlisle Bay, Barbados, 30 fms. ; and 

 an interesting young individual, about 16 mm. in diameter, with- 

 out a locality label but apparently from Barbados. This last 

 specimen has the primary spines very stout (15 mm. long by 2.5 

 mm. in thickness) and more or less flaring at tip. Owing to the 

 unusually well developed longitudinal ridges, the tips are quite 

 florescent. The peculiarities of this specimen are probably asso- 

 ciated with its youth, as the wear on the spines during maturity 

 and their tendency to become the abiding-place of bryozoans and 

 other fixed animals in their old age usually obliterate such fea- 

 tures as are here noted. 



STYLOCIDARIS AFFINIS 



Cidaris afflnis Philippi, 1845. Arch. Naturg., jhg. 11, 1, p. 351. 

 See Mortensen, 1903, Ingolf Ech., pt. 1, pi. I, fig. 1. 



Dorocidaris papillata A. Agassiz, 1872. Rev. Ech., p. 254 (in 

 part) ; pi. I, fig. 5. 



Stylocidaris affinis Mortensen, 1909. Ech. Deutsch. Siidpolar- 

 Exp., p. 52. 



All of the 5 specimens of this cidarid in the present collection 

 are young, the largest being scarcely half grown. The diameter 

 of the test is 9-17 mm. and the primary spines are 2-2.3 times as 

 much, as a rule. In one specimen, however, 11 mm. in diameter, 

 the primaries are scarcely 15 mm. long. There is some diversity 

 in the coloration of these individuals, for in some the brownish- 

 red lines and markings in the interambulaea and on the abac- 

 tinal system are quite distinct and in others they are nearly or 

 quite wanting. The youngest primaries (i. e., those on the upper- 

 mOvSt coronal plates) are normally quite different from the typ- 

 ical spines of the midzone, lacking the longitudinal dentate 

 ridges. Occasionally the difference is emphasized by color; in 



