304 Bulletin Vanderbilt Marine Mtiseum, Vol. VII 



Patella metallica, RoCHEBRUNE, DE, A. T., et Mabille, J., op. cit., 

 p. 91, pi. 5, fig. 5. 



Patella pupillata, Rochebrune, de, A. T., et Mabille, J., op. cit, 

 p. 92, pi. 5, fig. 6. 



Patella tincta, Rochebrune, de, A. T., et Mabille, J., op. cit., 

 p. 93, pi. 5, fig. 7. 



Genus: HELCIONISCUS Dall 

 Helcioniscus argentatus Sowerby 



Plate 117 



Type : The type was collected by Captain Beechey's voyage in 

 H. M. S. "Blossom" at Tahiti, according to Dr. H. A. Pilsbry's 

 careful analysis; he points out that the published locality of 

 "Chile" is an error, due to an unfortunate mixing of the "Blos- 

 som's" shells. The type is deposited in the British Museum of 

 Natural History. 



Distribution : Hawaiian Islands, Society Islands, Littoral. 



Material examined : Two specimens, taken on the rocks, at 

 Hilo, Hawaii, December, 1928, "Ara" World Cruise. 



Technical description: Shell large, 88 millimeters long 

 diameter, 77 millimeters short diameter; height, 31 millimeters; 

 the apex in this specimen occurs 40 millimeters from the anterior 

 margin ; shell thick, wide, oval, slightly narrower on the anterior 

 third than on the posterior portion, of a conical-dome shape with 

 convex slopes, apex subcentral, being very slightly anterior in 

 young specimens ; surface sculptured with numerous small, close- 

 set, unequal, radiating riblets, 56 in the present specimen, which 

 render the margin weakly crenulate and are reflected as fine, 

 radiating under lines on the inner surface. The colour is chestnut 

 brown with coppery tones on the outer surface ; the interior has 

 a large, pure white central callus, bordered by a dull whitish zone 

 around the muscle impression, beyond which the wide circumf eral 

 zone is shining opalescent pale golden or silvery with delicate 

 tones of lilac-rose blue or pale green, the marginal line being 

 narrowly chestnut brown. 



