394 MOLLUSKS OF TlIK GALAPAGOS — STEARNS. 



Section SIMPULUM Klein. 

 68. Tritonium (Simpuliim) olearium Linu*^. 



Bench, frnfj;iiuMil. 



liuU'r:itii;:iblc Island. A part only of a specimen, but sufficiently 

 larjj^e nnd in .iioocl enouji'li condition, so that the determination was not 

 (lilhcuU. Dr. Jones detected this species on the coast of South Amer- 

 ica, at iAIanta, in Ei'uador; also at I'ayta, in I'ern. The Alhjtross and 

 Jones collections greatly extend the previously well-known wide dis- 

 (libntion of this form. Its .c:eof>-ra])hical range is seemingly world-wide 

 within tropical and seniitropical waters. 



Family CASSIDID.E. 



(JiMuis CASSIS liainarclv. 



Subj;;tMms CYPR^CASSIS Stiilchlmry. 



69. Cassis (Cypraecassis) tenuis (Jray. -^ C. Massenw Kieuer. 



Common along the shores and the beaches. 



James, Charles, Hood, and Indefatigable islands. The (lalapagos 

 group, if we may judge by number of intlividuals and the sturdy 

 growth and size many of them exhibit, is the metropolis of this tine 

 si)ecies. From Indefatigable the largest specimen measured 5^ inches 

 in length, with three to four conspicuous rows of nodules on the body 

 wluu'l. An example sonunvhat larger from Hood Island, is about ">.;V 

 inclies long, and nearly as heavy as an average indiviilual of the Indo- 

 Paeitic Cassis nifiis of same length. In Tryon's monograph of the 

 C<(Sf<i<li(J(V this s])ecies is credited to the (lalapagos only; it occurs 

 however in the Gulf of California; the largest example from the Gulf 

 region that I have seen is nmch smaller and less heavy than the max- 

 imum specimens from the Galai>agos. A tine exami)le from the Gala- 

 pagos obtained by the late J. A. iMcNiel, measured nearly (j inches in 

 length. 



CJoims ONISCIDIA Swainsou. 



70. Oniscidia tuberculosa Kvo. 



Common on the beaches. 



James, Hood, and Indefatigable islands. An abundant species at 

 James Island where forty six shells were obtained; less nunuM'ous at 

 Indefatigable (Mus. Nos. 101* 103, IUL'370). Dr. Jones obtained it at 

 Chatham Island. 



Family CYrR^ID.E. 



ruMuis CYPRiEA Linno. 



71. Cypraea exanthema l.iiiu., vnr. - C. cervinetta Kien 



Ucaches, not unconnnon. 



James and Indefatigable islands. This form has a wide distribution, 

 from Payta, Peru, in the south to the (lulf of California and La Paz, 



