76 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [370} 
The Mysis stenolepis SM1ITH, (Plate ILI, fig. 12, female,) is often very 
abundant in such situations. The small young ones have been taken in 
May, and the half-grown ones later in the season. In the early spring 
the adult females, with eggs, occur in great numbers among the eel- 
grass, in estuaries and ponds. Mr. Vinal N. Edwards caught a large 
number in a small pond at Wood’s Hole, April 1. No males were found 
at this time with the females; the only adult males observed were taken 
in autumn. Possibly the males do not survive the winter. The adult 
females have not been observed in summer, and they probably die after 
hatching their young in the spring. The whole body is translucent ; 
each segment of the body has a stellate black spot; and there is more 
or less blackish pigment on the caudal lamellie, telson, antennal scales, 
and inner flagellum and peduncle of the antennule. This species con- 
tributes largely to the food of many fishes. The other species, J/. Amer- 
icana SMITH, also lives among eel-grass, as well as in deeper water off 
shore among alge. This has been found in large numbers in the stom- 
achs of the shad and the spotted flounder. 
Of Amphipods there are comparatively few species. The Unciola 
irrorata (p. 340, Plate LV, fig. 19) is pretty common here, as elsewhere. 
The Amphithoé valida SM1vH (p.315,) is often met with among eel-grass. 
Another species, A. compta SMITH, also occurs in the same places. 
It differs from the preceding in many characters, but may easily be dis- 
tinguished by its red eyes. <A third species of the genus, A. longimana 
SMITH, is also found among eel-grass. It has black eyes. The Coro- 
phium cylindricum and Gammarus mucronatus occur among eel-grass and 
algve, often in great numbers. 
Of Isopods there are several species. The Idotea irrorata (p. 316, 
Plate V, fig. 23) is common wherever eel-grass is found. The Hrichso- 
nia attenuata LARGER, (Plate VI, fig. 27,) is also found clinging to 
eel-grass in muddy situations. The Hpelys trilobus (Plate VI, fig. 28) 
is found creeping about over the bottom or among and beneath the 
decaying vegetable matter and mud usually to be found in sheltered sit- 
uations. It is usually so covered up with adhering dirt as readily to 
escape observation. The Hpelys montosus also occurs in similar situa- 
tions. 
Whenever lumber or drift-wood has been left for some time on the 
muddy shores it is found to be more or less eaten by the Limnoria lig- 
norum, (Plate VI, fig. 25.) This small isopod gnaws its galleries in the 
wood to a depth of about half an inch from the surface, and after a 
time these galleries become so numerous that the superficial layer will 
be completely honey-combed, and it will then scale off and another layer 
will be attacked. This little creature often does great damage to the 
piles of wharves and other kinds of submerged wood-work in this re- 
gion, and will be mentioned again in discussing the animals inhabiting 
piles, We. 
The ‘ horse-shoe crab,” Limulus Polyphemus, (p. 540,) is also common 
