30 
AMERICAJT JOURNAL 
REMARKS ON THE ANATOMY OF THE GENUS SIPHO- 
NARIA, WITH A DESCRIPTION OP A NEW SPECIES. 
ET WM. H, DAL Lj SMITHSONIAN INSTITUTION. 
The genus Siplionaria, described by Sowerby in 1824, is one 
of thè most natui’al and homogeneous instituted at that early day. 
It comprises some ninety species, principally from thè tropics, 
but has representatives in most parts of thè temperate zone. 
Probably thè most northern species yet described is one men- 
tioned in this paper — S. thersites, Cpr., from Sitka and thè 
coast of Alaska in lat. 57° N. 
If a conchologist were to take a specimen of this species in 
one hand and in thè other a specimen of S. gigas, Sby., from 
Panama, he would hardly be inclined, however, to place both of 
them in thè same group. One is smooth, horny and minute, 
with thè apex subterminal, and thè siphon rib very large ; and 
thè other is very large, solid and heavy, with thè apex centrai, 
and no outward indication of thè siphon. Between these forms, 
however, we find gradations ; yet thè genus, from thè shells 
alone, may be separated into two naturai groups, perhaps of 
subgeneric value, of which one contains thè greater proportion 
of thè species. The dentition of a species of Stphonaria (spe- 
cific name not given) is figured by Woodward in his manual, and 
has been copied by all subsequent authors, or described (as by 
H. and A. ikdams) as repfesenting thè dentition of thè genus. 
The species is from thè Cape of Good Hope, and from that 
locality all thè described species belong to thè S. sipho group. 
I bave not been able to obtain thè soft parts of more than one 
of thè species of that group, to confirm Woodward’s figure. 
The examination of sevepjil species of thè group typified by 
S. thersites, shows a decided^difference in thè dentition. 
The following is suggested as an arrangement of thè family : 
r 
