534 PROCEEDINGS OF THE NATIONAL MVSEUM. vouxxiv. 
tiinos the varices sire obsolete. The operculiun is short and wide with 
an apical nucleus, but with purpuroid markings on the inner face. In 
each group a transition toward the other section may be observed in 
some species. Both agree in dentition and station. In the majority 
oi species there is occasionally developed a carina at the shoulder over 
which the varices are elevated into spines or elevated scales. 
There are, however, species which alwa3^s have an angle or varical 
spine at the shoulder. The development of the varices is difi'erent 
in ditt'ercMit individuals of the same species, as in Murex; specimens 
from a lin(^ sand}" or soft l)ottom will frequently have remarkal)ly 
broad, thin, expanded varices; while those from an unfavorable situs, 
as a grav(dly l)()ttom, may have the varices degenerated to mere lines 
hardl}" raised above the surface except at the shoulder. These dif- 
ferences, though systematically not important, affect the general 
appearance of the shell very much and are liable to mislead students 
unfamiliar with the group into an undue multiplication of species. 
On the other hand the general impression of varia))ilit3' which these 
nuitations give is apt to lead to the ignoring of real differences of a 
more stable kind, and hence several very distinct species have been 
consolidated b}- too hast}' monographers. 
The species which have a small compact bod}' and spire, coronated 
with spines, and a long rather straight canal, have been separated as a 
section PagoduJa by Monterosato in 1884, with B. carinatus Bivona, 
as type; 1)ut taken in connection with other species, these, like the 
species of Troj^hojioj^sis, gradually merge into the typical form of 
the genus, even within the limits of the more variable species. A 
group which perhaps deserves distinction is that which I will call 
Aetivoirophon^ based on B. actinopJtorus Dall, in which with the 
structure of the thin Boixotrophon with long coronating spines is 
united a feature, not elsewhere noted in the genus, of successive 
canals, so curved that the projecting old ones, recurving from the 
siphonal fasciole form a whorl of hollow split spines, diverging from 
a deep umbilical pit, as in some murices. In Murex., however, the 
canal is closed and the aperture has a projecting callous margin. 
Another- group, possibly worthy of sectional distinction, appears in 
the fauna of southern California, where it is represented by Tmphon 
trUiiK/uJatus Carpenter, T. cerroseiisii^ Dall, and T. pinnatus, new 
species. These forms are large, with prominent varices, hardly any 
spiral sculpture, and brown or yellow coloration. They have the 
typical purpuroid operculum of the Antarctic Trtphon, but not its 
stumpy form or coarse reticulate sculpture. The siphonal fasciole is 
more or less gyratory and between it and the edge of the aperture is a 
distinct um))ilical chink or even a deep perforation. If these are con- 
sidered sufKcienth' marked to deserve a sectional name, they may be 
I'eferred to the genus Tr(p]u>)i with that rank, under the name of 
Austrotvipfi on . 
