OF CONCHOLOGY. 119 



to me, in San Francisco ; indeed I am only aware of the type 

 and the two other specimens just mentioned. 



Terebratella caurina, Gld. — Plate 6, fig. 1, 2, 3. 



Terehratula caurina, Gld., Proc. Boston Soc. Nat. Hist. vol. 



iii, Dec. 1850. Exped. Shells, p. 468, pi. 44, fig. 582. 

 Terebratella caurina, Gld. (emend), Otia Conch, p. 97, April, 



1862. Cpr., Check List W. C. Shells, p. 1. Cpr. 



Suppl. Rep. Brit. Assoc, p. 636, 1864. Cooper, Geog. 



Cat. p. 3, No. 8, 1867. Suess, Wohns. i, p. 25, 1859. 



Hah. Puget Sound to Sitka. Swan. Dall. Smithsonian Cab- 

 inet, 5964 (type), 13,610, 3368, 4177,4338, 11,785, 11,787. 



This species was abundantly obtained at low water mark, ad- 

 hering to the under surface of large stones and to each other, at 

 Sitka, Alaska Territory. Some young shells, perhaps of this 

 species, were dredged off the peninsula of Aliaska. Puget 

 Sound and Neeah Bay have also furnished specimens. 



The very large number of specimens thus obtained afforded an 

 unusually good opportunity for forming a correct idea of the 

 amount of variation possible in a single species. It is a typical 

 Terebratella, as the apophyses, which are well preserved in the 

 type, show. 



The latter is a small and quite regular specimen, with an ill- 

 defined broad mesial ridge in the neural, and depression in the 

 h?emal, valve. 



It has about fourteen subequal radiating ridges, the area 

 broad, hinge line nearly straight, deltidia widely separated, 

 foramen incomplete, large, overshadowed by the sharply pointed 

 apex of the neural valve, which is not truncate and resembles the 

 neural apex of Rhynchonella. It is of a grayish ash color, -6 of 

 an inch wide and -5 long. 



The examination of sixty specimens from Sitka gave the fol- 

 lowing range of variation : 



Greatest width, 1-8 inch. Greatest height, 1-7 inch. Diam- 

 eter of most inflated specimen, 1-2 inch. The most transverse 

 specimen measured 1*8 inch wide by 1-2 inch long. The most 

 produced specimen measured "7 inch long by -4 inch wide. The 

 most compressed specimen was '35 inch diameter by 1*25 Avide 

 and -75 long. 



The colors were usually of a deep crimson mixed with yellow, 

 quite different from the bright color of T. coreanica, and W. 

 G-rayi ; but they varied from light ashy yellow to a very dark 

 livid purple, and the epidermis from clay color to blackish 

 brown. The color was sometimes stronger on the lines of growth 



