BIOLOGICAL SURVEY OF WOODS HOLE AND VICINITY. I4!I 
prevalerce in the middle of the Sound near the western end. The bottom here is largely 
of clean sand and many typical sand-dwelling species, such as Echinarachnius parma 
and various flounders, consequently flourish in this area. Cancer borealis and Pagurus 
acadianus, on the other hand, are probably limited to the deeper waters on account of 
the lower temperatures prevalent there. The latter species was taken only four times 
by the Phalarope, though dredged at 41 of the Fish Hawk stations in Vineyard Sound. 
Among our local decapods we find a number of cases where interesting differences 
of habitat are displayed by the various species within a genus. Only a few such may 
be mentioned here. The differences in habitat shown by the two local members of the 
genus Cancer have already been referred to. These differences seem to relate to tem- 
perature, depth (if this is really an independent factor), and perhaps to character of 
bottom. One Libinia (L. emarginata) is of almost universal occurrence throughout 
both the Bay and the Sound; the other (L. dubia) appears to be restricted to shallow, 
inclosed waters. Although it is known to be abundant at some of these points, we do 
not have a single authentic record of its occurrence in the dredgings.¢ The difference 
displayed by the various local representatives of the genus Pagurus have likewise been 
discussed in another connection. The almost complementary character of the distribu- 
tion patterns for P. acadianus and P. annulipes is especially to be noted. 
The following decapods were taken with the dredge during the operations of the 
Survey. The asterisk, as usual, denotes species which were recorded from 10 or more 
dredging stations. For all of these, charts have been plotted. 
Pandalus montagui. *Pelia mutica (chart 113). 
Pandalus leptocerus. *Libinia emarginata (chart 114). 
Hippolyte zostericola. ?Libinia dubia (very young). 
Spirontocaris groenlandica. *Cancer irroratus (chart 115). 
Spirontocaris pusiola. *Cancer borealis (chart 116). 
*Crago septemspinosus (chart 107). ?Callinectes sapidus (fragment). 
*Homarus americanus (chart 108). *Ovalipes ocellatus (chart 117). 
Callianassa stimpsoni. Panopeus herbstii. 
*Pagurus pollicaris (chart 109). *Neopanope texana sayi (chart 118). 
*Pagurus acadianus (chart 110). Hexapanopeus angustifrons. 
*Pagurus longicarpus (chart 111). *Pinnotheres maculatus (chart 119). 
Pagurus kroyeri. Pinnixa chetopterana. 
*Pagurus annulipes (chart 112). Pinnixa sayana. 
Heterocrypta granulata. Dissodactylus mellite. 
Hyas coarctatus. 
Grouping, as usual, the more prevalent species according to the extent of their 
known range upon our coast,? we have— 
Predominantly northern forms. 
Homarus americanus.......... Labrador to New Jersey. 
Pagurus acadianus............ Grand Bank of Newfoundland to the mouth of Chesapeake Bay. 
(Northern ?). 
@ A few small specimens were thus identified at first, but further quite extensive collecting has thrown doubt upon these 
determinations. 
+ We are indebted to Miss Rathbun for these statements as to range. 
