MARINE MOLLUSKS OF THE GALAPAGOS 117 



fPyramidella (Triptychus) olssoni Bartsch 



Pyrene castanea (Sowerby) 



Pyrene fuscata (Sowerby) 



*Pyrene haemastoma (Sowerby) 



'\Pyrene lucasana (Dall) 



*Rissoina dina Bartsch 



fRissoina cf. R. laurae (de Folin) 



fRissoina signae Bartsch 



fSeila assimillata (C. B. Adams) 



Serpulorbis margaritarum (Valenciennes) 



Strombus granulatus Swainson 



fSulcoretusa luticola (C. B. Adams) 



*Tectarius galapagiensis (Stearns) 



*Tegula cooksoni (E. A. Smith) 



*Tegula snodgrassi (Pilsbry & Vanatta) 



*Terebra albemarlensis Dall & Ochsner 



Thais callaoensis (Gray) 



Thais columellaris (Lamarck) 



Thais (Vasula) melones (Duclos) 



Thais patula pansa (Gould) 



Thais planospira (Lamarck) 



Thais speciosa (Valenciennes) 



*Tralia vanderbilti Schwengel 



fTricolia perforata (Philippi) 



*Triphora galapagensis Bartsch 



*Tri'via fusca (Gray in Sowerby) 



*Trivia maugeriae (Gray in Sowerby) 



*Trivia pacifica (Gray in Sowerby) 



*Turbonilla (Chemnitzia) houseri'DaW & Bartsch 



*Vanikoro galapagana Hertlein & Strong 



Vermetus cf. V. complicatus (Dall) 



fFermicularia pellucida eburnea (Reeve) 



*JVilliamia galapagana Dall 



The temperature of the surface waters about the Galapagos Islands 

 varies greatly at times. Records show variation of from 66°F. to 86°F. 

 These differences in temperature are due chiefly to the influences of the 

 various currents, the warm south Equatorial Current and Equatorial 

 Countercurrent, and the cool Humboldt Current. Although at times 

 the waters are quite cool for equatorial latitudes, their general condition 

 is decidedly warm, as indicated by the presence of tropical and sub- 

 tropical genera and subgenera of mollusks such as Antigona {Peri- 

 glypta), Area {Area), Cassis (Cypraeeassis), large Conus, large Fas- 

 ciolaria, Morum, Murex (Alurieanthus) , Strombus. 



The present list is comprised of 164 species and subspecies, 37 

 pelecypods and 127 gastropods. The identifications of six of these are 

 uncertain but they are compared to known species. In addition to the 

 foregoing, ten species are present which, because of their imperfect preser- 

 vation or for other reasons, are cited as to genera only. Among these is 

 one genus (Haminoea) here recorded from the islands for the first time. 

 Fifty-five species and subspecies in this list were originally described 



