322 PROCEEDINGS OF THE ACADEMY OF [Nov., 



cuticle, in lai'ge part deciduous, chiefly preserved near tlie posterior 

 end, and bearing very delicate raised concentric striae. Beaks are 

 rather prominent. The hinge-line is short, slightly curved under 

 the beaks. Internal margins smooth. The interior is colored like 

 the outside but usually brighter in tone. 



Greatest length 12.5, greatest breadth 6.5, diameter 6.5 mm. 



Greatest length 12.8, greatest breadth 8, diameter 7 mm. 



There is considerable variation in contour. The largest valve 

 seen, from Moomumi, Molokai, measures, length 19.3, width 10.2, 

 semidiameter 4.8 mm. 



Oahu; Rabbit Island; Paumalu; Mokapuu Point (type loc), 

 Honolulu Harbor. Molokai: Moomomi, Pukahaku. Midway 

 Island. Pearl and Hermes Reef (W. A. and E. J. Bryan). 



Modiolus peasei Newcomb. 



1870. Amer. Journ Conch. V, p. 163, pi. 17, fig. 7. ("Sandwich Islands, 

 dredged in 12 fms., outer harbor of Honolulu"). 



Off Honolulu in 6 fathoms, D. B. Langford, 1915; Off Mala Bay, 

 West Maui, 21 fathoms, Thaanum and Langford, 1918. Fi'om the 

 second locality there are very fine specimens, up to 31 mm. long. 



Mytilus crebristriatus Conrad. 



1837. Conrad, .lourn. Acad. Nat. Sci. Phila. VII, o. 242. 

 1916. Bryan, Nat. Hist, of Hawaii, p. 4.57, pi. 104, fig. 1. 



Oahu: Honolulu Harbor; Pearl Harbor. Molokai: Kainalu, Ha- 

 waii: Hilo. 



The large typical form of this species is particularly abundant in 

 Pearl Harbor and the adjacent fossil deposits. In Honolulu it 

 occurs on the Kewalo reef, off the mud flats where considerable 

 fresh water comes in, and Melania mauiensis is abundant. Prob- 

 ably typical M. creh) istnaius occurs only where the sslH water is 

 slightly diluted with fresh; on open shores it is replaced by a small 

 form. 



The usual length of M. crehristriatus is from 25 to 35 mm. So far 

 as we know, the only published figure is that in Bryan's Natural 

 History of Hawaii. 



A very thick form was found fossil at Waimanalo, Oahu, by Prof. 

 Bryan. 



On most of the open beaches a small form, which may be called 

 form mantima, is found in abundance; the length is 10 to 15 nmi. 

 Localities for this form follow, mainly from the Bryan collection. 



