162 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
uniting the shell but not anteriorly. The protoconch is orbicular. 
At a later stage the shell broadens posteriorly being twice the 
height of the anterior portion (Fig. 18, c). As it approaches the 
mature stage the growth narrows posteriorly and the shell 
becomes more elongated (Fig. 18, d). The syphons are united 
and project only a short distance beyond the edge of the shell. 
The valve is very long and marked at the base by an encircling 
band of nearly black lines broad at their bases and crowded 
together. A few large tentacular papillae rise from the remaining 
portion of the syphon. Eight large, blunt papillae fringe the 
opening of the branchial syphon. These are dotted with black. 
Many smaller papillae mark the surface of the syphon. The 
anal papillae are mottled with white dots. The foot is long, 
narrow, and grooved below. In classification Pandora and 
Lyonsia are placed close together. As will be seen by the figures 
there is not the slightest resemblance between them except that 
the syphons are united and the shell nacreous. 
CYPRINA ISLANDICA (Linn6). 
Fig. 19. Length, 81 mm. 
Fig. 19. — Cyprina islandica (Lian6). 
