BIOLOGICAL STUDY OF CHESAPEAKE BAY WATERS 
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Collodes robustus Smith was dredged in water from 102 to 328 meters, but in 
other regions it has been found at from 90 to 683 meters (Rathbun, 1925, p. 119). Its 
known distribution is from Massachusetts to North Carolina, and it has been found 
during all seasons of the year. Ovigerous specimens have been caught off Virginia 
in March and off Massachusetts in August and September. 
Rathbun’s subspecies marthae of Euprognatha rastellifera A. M. E. has been 
dredged off Chesapeake Bay in water varying in depth from 105 to 306 meters, but 
farther north it has been found in water from 81 to 419 meters deep. It has been 
collected at all seasons of the year, but only one specimen, according to the records 
published by Rathbun (1925, p. 98), was found with eggs. This individual was 
collected in July off Marthas Vineyard in exceptionally shallow water (81 meters) 
for that species. 
Euprognatha rastellifera acuta A. M. E., which is the more southern subspecies 
(Habana, Porto Rico) but which has been found as far north as near Marthas Vine- 
yard, is probably represented in our collection by one juvenile specimen. This was 
taken off the mouth of the bay in 102 meters of water. 
Hyas coardatus Leach, which is commonly called the toad crab, has been dredged 
along the Atlantic coast of North America from Newfoundland to North Carolina. 
The records of Rathbun (1925, p. 260) show that it occurs in water ranging from 9 to 
about 350 meters. It has not been found in the bay, but a few specimens have been 
taken off of the coast of Virginia. 
The so-called common spider crab, Libinia emarginata Leach, occurs in Chesa- 
peake Bay, but it has been brought to light only by dredging in water ranging from 
7 to 46 meters. All of the specimens collected were from the extreme southern part 
of the bay where the salinities near the bottom ran from about 21 .00 to 31 .00 per mille, 
and the water temperatures from 8.8° C. to 21.9° C. It was caught several times at 
areas G, G' , and A. A few specimens have been found also in Hampton Roads and 
off the Inner Middle Ground . There is one specimen in the Chesapeake collection of 
the United States National Museum which came from outside of the bay, off Virginia 
Beach. Libinia emarginata has been dredged during all seasons of the year, but the 
rec.o'rds show no ovigerous individuals. Most of the specimens are in the juvenile 
condition. Rathbun (1925, pp. 311-313, pp. 314-317) records its distribution along 
the Atlantic coast of North America from Nova Scotia to West Florida, and she finds 
it occurring on all sorts of bottoms in comparatively shallow water. 
Another spider crab, Libinia dubia M. Edw., is much more widely distributed 
over Chesapeake Bay than the former species, and apparently in some localities at 
least it lives in shallower water (Rathbun, 1925, p. 318). It has been collected at 
areas A, D, E, H, and T, the latter area being off Love Point, not far from Baltimore. 
In addition it has been taken in the following localities: Hampton Roads, Norfolk, 
Chincoteague, Tangier in Virginia, and off the mouth of the Rappahannock River, 
off York Spit, Thomas Point, and Tilghman Island. Apparently L. dubia is more 
at home in Chesapeake Bay than any other spider crab, but we have no records of 
its occurrence in the rivers. Possibly the lack of specimens from such localities is 
due to the fact that very little dredging has been undertaken in the rivers, although 
we are not accustomed to think of spider crabs as frequenting water of very low 
salinity. While L. dubia is known to range along the Atlantic coast from Cape Cod 
down into the Gulf of Mexico, no specimens have been reported outside, in the region 
of Chesapeake Bay. Undoubtedly this form may live in water of low salinity, for 
