BIOLOGICAL STUDY OF CHESAPEAKE BAY WATERS 
355 
and that it has only a slightly calcified integument suggests to Caiman that it is 
adapted for a partly pelagic life. Fish (1925, p. 152) found it in the plankton in 
greater numbers during the breeding season and most abundant usually after a storm. 
Ten specimens were captured at area K, off the mouth of the Potomac River, in 
May, 1920. It is not known at what depth they were taken; but the bay at that 
area was 10 meters deep, and the bottom was of yellow sand. The salinity ranged 
from 11.15 per mille at the surface to 13.09 per mille at the bottom. 
DECAPODA 
The Chesapeake survey is fortunate in having the aid of the United States 
National Museum for the identification of the decapod Crustacea. It is indebted to 
the division of marine invertebrates of that institution, and especially to Dr. Mary J. 
Rathbun and to Dr. Waldo L. Schmitt, who have generously studied, identified, and 
listed the various decapods collected on our cruises. 
It is important to note that the lists given below not only include the specimens 
taken by the Chesapeake survey but also those which have been collected from 
Chesapeake Bay and vicinity during the last 50 years. These specimens have been 
deposited in the United States National Museum and identified by its staff. Conse- 
quently, the material has been collected in various ways, such as by dredging, trawling, 
and towing in the offshore waters, by seining near shore, by collecting along the tide 
lines, by collecting in marshes, rivers, and creeks connected with Chesapeake Bay, 
and by dredging, trawling, and towing immediately outside of the mouth of Chesapeake 
Bay. 
The three lists which follow deal with Chesapeake Bay only and are little more 
than records of the names of species and the regions in which they have been found. 
They are not intended to show the limits of distribution, since much of the material 
is not the result of systematic collecting over the whole bay. The distribution of 
species in Chesapeke Bay, so far as the author considers permissible from the data, 
will be given in other lists. 
Upper bay only {north of the mouth of the Potomac River ). — One species of decapod, 
Pinnixa sayana Stimpson, was taken from the upper part of the bay and from no 
other region. The records in this case show that it was collected only on two occa- 
sions. Since this species probably lives in the tubes of annelids and since no special 
effort was made to find it, the data are insufficient to d^aw any conclusions as to its 
distribution. 
Lower bay only . — Shrimps: Penaeus selifera (L), P. brasiliensis (Latr.) (probably), Trachy- 
penaeus constrictus (Stimpson), Parapenaeus constrictus (Stimpson), Hippolysmata wurdemanni 
(Gibbes), Crago packardi (Kingsley), Hippolyte pleuracantha (Stimpson). Porcellanids : Euceramus 
praelongus Stimpson. Thalassinids: Callicmassa stimpsoni Smith, Upogebia affinis (Say). Hermit 
Crabs: Pagurus pollicaris Say, Clibanarius vittatus (Bose.). Crabs: Ovilipes ocellatus (Herbst), 
Portunus gibbesii (Stimp.), Arenaeus cribrarius (Lamk.), Cancer irroratus Say, Neopanope texana 
sayi (Smith), Panopeus herbstii Edw., Pinnotheres maculatus Say, Pinnotheres ostreum Say, Pinnixia 
cylindrica (Say), Pinnixia chaetopterana Stimpson, Ocypoda albicans Bose., Uca pugilator (Bose.), 
Uca pugnax (Smith), Libinia emarginata Leach, and Pelia mutica (Gibbes). 
Upper and lower bay . — Shrimps: Palaemonetes carolinus Stimpson, P. vulgaris (Say), Crago 
septemspinosus (Say). Hermit Crabs: Pagurus longicarpus Say. Crabs: Callinectes sapidus Rath- 
bun, Hexapanopeus angustifrons (Benedict and Rathbun), Rithropanopeus harrisii (Gould), Eury- 
panopus depressus (Smith), Sesarma ( Holometopus ) cinereum (Bos.), Uca minax (LeConte), and 
Libinia dubia M. Edw. 
1988—30 6 
