CIDARIS METULARIA. 385 



Cidaris metularia 



! Cidaris metularia Blaixv., 1830. Zooph. 



! CidarUe.1 metularia Lame., 181G, An. s. Vert. 



PI. P.f. 28, n ; PL P.f. i ; PI. XXXV. f. s. 



Abactinal system sparsely covered by minute miliary spines and small 

 pedicellarise mounted upon brilliant glassy tubercles. A ring of larger 

 miliaries surmounted by spines surrounds the whole abactinal system. Geni- 

 tal plates large, trapezoidal in contact ; anal system pentagonal, one row of 

 large plates on side next madreporic body ; ocular plates triangular. In the 

 ambulacra the outer rows of secondary tubercles adjoining the poriferous 

 zone are large, with two inner vertical rows of small miliaries, well defined, 

 extending along the ambulacra] zone. The median interambulacral space 

 filled with broad flat miliary tubercles, with indistinct mammary boss, in 

 striking contrast to the prominent secondary tubercles surrounding the small 

 scrobicular circle of the primary interambulacral tubercles. The striation of 

 the spines is fine; the granulation exceedingly coarse, especially in young 

 specimens; granules distant. The spines are more frequently colored by 

 transverse bands than either in C. tribuloides or C. Thouarsii. The color of 

 the secondaries and papillae is light violet, darker at tip, those of the ambula- 

 cra! region usually darker than the interambulacral secondaries and papillae. 

 The median interambulacral zone of C. metularia is much narrower than the 

 corresponding zone of specimens of the same size of C. tribuloides. 



Red Sea ; Mauritius ; East India Islands ; Sandwich Islands ; Feejee Islands. 



Cidaris Thouarsii 



! Cidaris Thouarsii Val., 1846, Ac Df.s. C. R. Ann. Sc. Nat., VI. 



PL P.f. i-5"; PL XXXV. f. 2; PL XXXVIII. f. 1,2. 



Genital plates elongate, tapering ; genital openings large, only partly 

 covered by miliaries ; outer edges of plates adjoining anal system bare ; 

 plates of anal system much smaller than in C. tribuloides, extending towards 

 the ocular plates, forming a stelliform abactinal system ; the genital plates 

 completely separated by a large anal plate projecting between them from 

 the anal system. Ocular plates elongate, smaller than in C. tribuloides. 



Ambulacra narrower than in C. tribuloides, with a single irregular vertical 

 row of small miliaries between the two exterior main rows. The principal 

 interambulacral tubercles separated by a narrow zone of miliaries of nearly 

 the same size as the secondaries forming- the large scrobicular circle. The 



