56 
MARINE SHELLS OF WEST COAST OF NORTH AMERICA 
The interior is usually polished, except on the muscular impressions, 
which are granulous and strongly impressed. The scar is horseshoe¬ 
shaped, the right anterior limb broad near its extremity. Close to the 
anterior extremity of the left limb is a small oval scar indicating an 
attachment of the mantle of the shell. The apex is posteriorly curved, 
subcentral, smooth, and in the youngest specimens I have seen exhibits 
no tendency to spiral growth. In older specimens it is usually somewhat 
eroded. The texture of the shell is exceedingly solid, porcelainous, and 
strong. Old individuals fill up the cavity of the apex while adding to the 
margin. From the irregularities of their stations most fantastic forms 
occur. (Dali.) 
Type in British Museum. Type locality, Valparaiso. 
Range. Trinidad and the Farallon Islands to Chile. 
Described as Mouretia reticulata by Sowerby. 
Family SIPHONARIIDAE 
Genus SIPHONARIA Sowerby, 1824 
Shell ovate, above rather depressedly conical, beneath concave; vertex, 
when not eroded, obliquely turned backwards, exactly in the opposite 
direction to the canal, which is on the right side. Within, the muscular 
impression is observable ; it is commonly very distinct, and nearly sur¬ 
rounding the inside at rather less than halfway from the edge to the 
lowest point; interrupted in front by the head of the animal, and on one 
side by the canal, so that between the canal and the head, there is an 
irregularly subcircular muscular impression only connected with that of 
the other side of the shell by a very narrow line, over which lies the head 
of the animal; the extremities of the muscular impression are rather 
expanded, particularly that immediately behind the canal. The canal 
itself sometimes forms a distinct groove within the shell, running from 
the vertex to the margin, and a corresponding prominence may be observed 
on the outside, forming a ridge from the vertex to the margin; but the 
internal groove and the external ridge are not always distinct; the place 
of the head and that of the canal can, however, be easily distinguished 
in all cases. (Sowerby.) 
Type. Siphonaria sipho Sowerby. 
Distribution. Cape, India, Philippines, Australia, New Zealand, 
Pacific, Galapagos, Peru, Cape Horn, California. Fossil : Miocene . . . . 
[561 
