372 
BULLETIN OF THE BUREAU OF FISHERIES 
off Bloody Point in waters the salinities of which ranged from about 26.00 to 16.00 
per mille. 
53. The only cumacean found on our cruises was probably Oxyurostylis smithi. 
Several specimens were captured in May, 1920, off the mouth of the Potomac River. 
54. Collections of decapods made in each case in a similar manner, at different 
seasons during the year, and at widely distributed areas in the offshore waters of the 
Chesapeake Bay did not bring to light any species confined to the upper half of the 
bay. On the other hand, a number of species have been found only in the lower 
part of the bay and outside. 
55. Of the 18 species of shrimps or shrimplike forms only Palaemonetes carolinus, 
P. vulgaris, and Crago septemspinosus have been found in abundance. P. carolinus 
frequents shallow water along the tide lines and flourishes in water of low salinity. 
It breeds in the summer time and may be found many miles up rivers where the water 
is almost fresh. P. vulgaris, on the other hand, has not been reported from river 
waters, although it is found in shallow waters near tide lines. It has a summer breed- 
ing season. C. septemspinosus frequents the deeper areas of Chesapeake Bay, but it 
also, like P. carolinus, has been found in some of the rivers. Ovigerous specimens 
have been collected at all seasons. 
56. Two species of hermit crabs, Pagurus longicarpus and P. pollicaris, have 
been found in considerable numbers. Both were confined almost entirely to the 
region extending from the mouth of the Potomac River to the mouth of the bay. 
Specimens were captured in waters ranging from about 18.00 to 31.00 per mille in 
salinity and were found at all seasons during the year. An ovigerous specimen of 
the first species has been caught in the autumn, and several ovigerous specimens of 
the second species have been found in the spring. 
57. The common edible crab, Callinectes sapidus, which is such a familiar form 
along the shores of Chesapeake Bay, was taken infrequently in our dredging and 
trawling. Such specimens as were captured were usually juveniles. But in Decem- 
ber, 1920, off Old Point Comfort 32 female and 15 male specimens, mostly of large 
size, were caught in the trawl. All of these specimens were inactive, owing, no doubt, 
to the low temperature of the water (10.1° C.). It is well known that Callinectes is 
distributed all over the bay and well up into the rivers. Evidently individuals of 
this species can live in waters of wide ranges of temperature and salinity. 
58. The “mud crabs” are well represented, four species having been found. 
Two of these, Neopanope texana sayi and Hexapanopeas angustijrons, occurred in 
considerable abundance. The former has been caught only in the southern half of 
the bay, while the latter has a little wider distribution. Both species are to be found 
throughout the year, and they breed during the summer. They have been taken 
from waters of wide ranges of temperature and salinity. 
59. Five species of “commensal crabs” — three from the tubes of annelids, one 
from the oyster, and one from the mussel — have been collected. 
60. Spider crabs are classed as marine forms, but three species have been found 
in Chesapeake Bay. Libinia dubia has been taken in many places and as far north 
as Love Point, near Baltimore. No ovigerous specimens have been found, and nearly 
all have been in the juvenile condition. a 
61. The distribution of the Crustacea in the bay indicates that there are many 
forms which can live in waters of a wide range of salinities and temperatures. 
si 62. Horseshoe crabs have been found only at the areas close to the mouth of 
the bay. 
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