NO. 1264. ILLUSTRATIONS OF AMERICAN SHflLLS— BALL. 549 
thoni 1 idontitiod tho species with Carpenter's immature typ(^ and fioured 
])0th. ^ It is ahva3^s a little ditticult to be certain about such Identitica- 
tions, as the A'oung* of various species are very much alike, l)ut in this 
case both have the same form, color, and seven varices, and after 
reviewing- the matter 1 see no reason for changing- my original opinion. 
So far this species is only known from San Pedro Channel and Catalina 
Island in 30 to 90 fathoms. The adults are large, solid, and strong, of 
a streaked brown color, with seven varices, usually more or less chipped, 
the spinose prolongations wavy and more or less twisted and often 
verv long. There is an ol)Solete spiral striation and five or six whorls. 
The shell is much attenuated toward the canal, and reaches a length 
of about 100 mm. It has been obtained through the fishermen in con- 
siderable numbers. 
TROPHON CERROSENSIS Dall. 
This is a considerabh' smaller shell, more delicate and with more 
numerous varices. It is of the same general type as the preceding, 
but has well-marked spiral threading, about ten varices, and, Avith the 
same number of whorls, measures only about ¥) mm. in length. It is 
of a yellowish color, and has been dredged near Cerros Island, Lower 
California, in 9 to 48 fathoms. It is figured. ~ U. S. N. M. , 97072. The 
young shells are quite different from the young B. trlangulatuH^ being 
decidedly more slender and longer, with the same number of whorls. 
TROPHON PINNATUS, new species. 
Shell large, thin and delicate, with a low spire, seven to ten broad 
thin varices much expanded near the canal and elongated into spines 
at the shoulder; surface with fine incremental and obsolete fine spiral 
striation; there are about five whorls beside the nucleus, which be- 
tween the suture and shoulder are tabulate; the spines resemble those 
of the two preceding species; the aperture is rounded, with a long, 
wide, open canal, a strongly marked more or less imbricate siphonal 
fascicle, and a deep umbilical perforation; the color is white, pale 
brown, or more or less spirally banded brown or yellowish white. 
Long. 80; of aperture and canal 45; max. lat. (including spines) 57 mm. 
Dredged in Magdalena Bay and near Point Abreojos, Lower Cali- 
fornia, by the U. S. Fish Commission steamer Alhatrom at stations 
3040, 3043, and 3045, in 21 to 74 fathoms. 
This fine species belongs to the same group as the two preceding, 
and ma}" be distinguished from B. triangidatus^ which is nearest to it, 
by its more numerous varices and their wide expansion anteriorly, its 
deeply perforate axis, and the absence of the anterior attenuation, 
which is 80 noticeable in that species. It is also of a lighter and more 
iProc. of the U. S. Nat. Mus., XIV, 1891, pi. v, figs. 1, 3, and 6. 
^Idem, pi. V, figs. 5 and 7. 
