62 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [356] 
spawning in May, but at New Haven they spawn as early as March and 
April. It is probable that the period of spawning extends over several 
months. Mr. Sanderson Smith thinks that they also spawn in autuinn, 
on Long Island. It is not known how long a time each female requires 
for the formation of her string of capsules. There are two forms of these 
capsules, about equally abundant in this region. In one the sides of 
the capsules are nearly smooth, but the edge is thick or truncate along 
most of the circumference, and crossed by numerous sharp transverse 
ridges or partitions, dividing it into facets. Dr. Coues states that these 
belong to F. carica. An examination of the young shells, ready to leave 
the capsules, confirms this. The other kind has larger and thinner cap- 
sules, with a thin, sharp outer edge, while the sides have radiating 
ridges or raised lines.. Sometimes the sides are unlike, one being smooth 
and more or less concave, the other convex and crossed by ten or twelve 
radiating, elevated ridges, extending to the edge. This kind was attrib- 
uted to F. carica by Dr. G. H. Perkins, and formerly by Mr. Sanderson 
Smith, but a more careful examination of the young shells, within the 
capsules, shows that they belong to S. canaliculata. 
Among the sand-dwelling bivalve shells we find quite a number of 
species that burrow rapidly and deeply, some of them living in perma- 
nent holes or perpendicular burrows, into which they can quickly de- 
scend for safety, and others burrowing in the sand in all directions, 
without permanent holes. 
The “razor-shell,” Ensatella Americana, (Plate XXVI, fig. 182, and 
Plate XXXII, fig. 245,) is a common inhabitant of sand-flats and sand- 
bars, where the water is pure, generally living near low-water mark or 
below, but sometimes found considerably above low-water mark, as on 
the sand"bar at Savin Rock. This curious mollusk constructs a deep, 
nearly round, somewhat permanent burrow, which descends nearly per- 
pendicularly into the sand to the depth of two or three feet. These 
holes can generally be recognized, by their large size and somewhat 
elliptical form, when the tide isout. Sometimes they are’very abundant 
in certain spots and not found elsewhere in the neighborhood. They 
sometimes come to the top of the burrow, when left by the tide, and pro- 
ject an inch or two of the end of the shell above the surface of the sand ; 
at such times, if cautiously approached, many can easily be secured by 
pulling them out with a sudden jerk, but if the sand be jarred the whole 
colony will usually take the alarm and instantly disappear. When thus 
warned it is generally useless to attempt to dig them out, for they quickly 
descend beyond the reach of the spade. They will often hold themselves 
so firmly in their holes by means of the expanded end of the long mus- 
cular foot, that the body may be drawn entirely out of the shell before 
they will let go. When not visible at the orifice they can often be se- 
cured by cutting off their retreat with a sudden oblique thrust of the 
spade below them. They are obliged to come up to the upper part of 
the burrow on account of the shortness of their siphons, or breathing- 
