ZOOLOGY. 371 



CHRYSODOMU3 SITCHENSIS. 



Chrysodomus sUchensis, CARP. Report to Brit. Assoc. 1856, p. 343. 

 Tritonium (Fusus) siichense, MIDD. Malacol. Ross. II, p. 149, No. 14 ; pi. 2, figs. 5-8. 

 Jl.jb. Straits of Juan de Fuca, Dr. Suckley,G. Gibbs, esq. ; Sitka, Mid. after Eschscholtz. 



Specimens of both mature and young shells were brought from the Straits of Fuca, where it 

 appears to be rare. They agree, in all respects, with MiddendorfFs plate and description. 



: Family 



NASSA MENDICA. 



Naasa mendica, GOULD, U. S. Expl. Exped. Mollusca & Shells, p. 263, and Atlas, fig. 331. 

 Hob. Puget Sound, Dr. G. Suckley. 



This as well as the following species appear to be rare. 



NASSA GIBBSII, n. s. 



DESCRIPTION. Form short and moderately ventricose ; whorls, six ; the body whorl nearly equalling the spine in length, 

 all cancellated, longitudinally ridged. Ridges, about 13 on each whorl, the intermediate furrows deep and equal in width 

 to the ridges. Mouth subovate, canal spirally twisted. 



Colors. Inside of mouth dark purplish ; epidermis smooth ; olivaceous brown. Indistinct bands visible inside, which, 

 under the epidermis, are found to be black or brown, varying in width and number, one usually distinct around the middle 

 of whorl. Long. 0. 40, lat. 0. 25. 



Five specimens of this Nassa more resemble N. trivittata than N. me?idica, having the band 

 ing and shorter form of the former, their breadth being equal, but length proportionately much 

 less than the latter, and, though smaller, their ridges are more strongly marked. Found dead 

 along the shore at Port Townsend, Puget Sound. Only one has a fresh appearance. 



PURPURA LACTUCA. 



Murex lactuca, ESCHSCHOLTZ, Zool. Atlas, II, p. 9 ; pi. ix, fig. 3, 1829 MIDD. Beitrage, II, p. 120. 



Murex ferntgineus, accidental variety, IDEM, id. pi. ix, p. 3. 



Purpura scptentrionalis, REEVE, Con. Icon. pi. x, p. 50. JAY, in App. to Perry s Exp. to Japan, vol. II, pi. 5. figs. 16, 



17. CARPENTER, Rep. to Brit. Assoc. p. 340. 

 Muricidea lactuca, CARPENTER, Report, p. 345. 

 fftb. Sitka, Eschscholtz ; Puget Sound, Dr. Suckley & Mr. Gibbs ; Shoalwater bay and Straits of Fuca, Dr. Cooper. 



This is a remarkable and abundant species, which, with Reeve, we prefer to place in the 

 genus Purpura. Like others of that genus, it is subject to many variations, of which analogous 

 examples may be observed in P. lapillus more especially. The figures given by Eschscholtz, 

 Jay, and Reeve, represent three of these varieties, the first being at one, and the third at the 

 otber extreme of the series. After a careful comparison of more than two hundred individuals, 

 from various localities in Washington Territory, we find the gradation from one to -the other 

 so regular that we are forced to refer them all to one species, first established by Eschscholtz. 



&quot;This shell abounds in the middle parts of Shoalwater bay on rocks and oyster-beds, and 

 also in the deeper parts of Puget Sound. It appears to feed on oysters and other animal 

 substances. I have found one adhering to an oyster, which was perforated by a small, round 

 hole near the apex, and through which the periwinkle , as they are popularly called, appeared 

 to be devouring the animal. They can live several days out of water in damp places. 



The amount of rugosity seems to depend entirely upon the station the specimens are found 



