250 Bulletin Vanderbilt Marine Museum, Vol. VI 



to Zanzibar and Madagascar, to Australia in the Torres Straits 

 region and Queensland and the Tonga Islands, and northward to 

 the Loo Choo Islands. Its bathymetrical occurrence is from lit- 

 toral on the coral reefs down to 73 meters; this greatest depth 

 having been recorded by the "Siboga.'* 



Material examined: One unusually fine specimen taken at 

 Noumea, New Caledonia, September 19, 1931, by the "Alva." 



Colour: The living urchin has the secondary spines a rich 

 dark purple and the primary spines somewhat lighter purple, 

 sometimes with a faintly greenish tint, and not infrequently 

 banded with yellowish white. 



Discussion : The "Alva" specimen from Noumea, New Cale- 

 donia, has the test with a width diameter of three and a quarter 

 inches, height diameter of two and one-eighth inches, and the 

 primaries from four to four and a half inches long, with the col- 

 lar about one-quarter to five-eights of an inch long. There are 

 seven coronal plates present. The collar is unspotted, being a deep 

 dark purple. The primary spines are very characteristic, quite 

 stout, tapered distally and having very many close-set series of 

 granules, forming longitudinal lines. 



The "Alva" specimen is slightly larger than any of those ex- 

 amined by Dr. H. L. Clark in the British Museum collection and 

 also is apparently the first definite record of this species from 

 New Caledonia, which island, however, is well within the area 

 of its distribution. 



Dr. Mortensen has given us a characteristically thorough de- 

 scription of this species with an exhaustive bibliography (1928). 



References: Cidarites imperialis, Lamarck, J. B., Hist. Nat. 



Anim. sans Vert., t. II, 1816, p. 54 (refers to Seba's pi. 



13, fig. 3.— Agassiz, a., Rev. Echini, pt. Ill, 1873, pi. IF, 



fig. 2. 

 Phyllacanthus imperialis, CLARK, H. L., Catal. Recent Sea-urchins, 



Brit. Mus., 1925, p. 10. — Mortensen, Th., Monogr. of Echi- 



noidea, I Cidaroidea, 1928, p. 504, pi. 54, fig. 4 ; pi. 57, fig. 3 ; 



pi. 74, fig. 6 ; pi. 88, figs. 4-10. 



