172 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
cases with a double curve; some have truncate ends and are 
probably furnished with optical pigmentation. On the first 
mantle border a curious tri-knobbed papilla is seen at the end of 
the rows of imbrications that mark the shell and is evidently 
involved in their production (Fig. 27, a). Beyond this mantle 
Fig. 27. — Cardium pinnulatum Conrad. 
margin another one occurs, the edge of which is perfectly plain. 
A young shell less than a millimeter in length reveals the proto- 
conch (Fig. 27, 6). Instead of being orbicular it shows a beak- 
like projection posteriorly. It resembles a bubble from its glassy 
surface. The dorsal margin is straight with a few imbrications 
rising from it. 
LIOCARDIUM MORTONI (Conrad). 
Fig. 28. Length, 12 mm. 
The figure of the expanded animal in the Government Report 
upon the Invertebrate Animals of Vineyard Sound and Adjacent 
Waters does not bear the faintest resemblance to its appearance. 
The branchial syphon is short and broad, somewhat larger than 
the anal syphon. The edge of the opening is irregular and fringed 
with numerous short, pointed papillae; the anal syphon projects 
a long, slender valve with an encircling row of brown markings, 
and near the base longitudinal rows of brown dots. The 
branchial syphon is marked by a similar row of dots. The anal 
syphon represented by its valve is twice as long as the branchial 
syphon; a few hair-like papillae spring from the sides of the 
valve. Issuing from the base of the syphon just within the shell 
a brush of long and short papilla-like tentacles spread in various 
I 
