140 BULLETIN OF THE BUREAU OF FISHERIES. 



of general distribution. These types will be considered separately. The ranges here 

 stated have been furnished by Miss Rathbun. 



Species found predominantly in the colder "Jinters. 



Pagurus acadianus From the Grand Bank of Newfoundland to the mouth of Chesapeake 



Bay. 

 Cancer borealis Nova Scotia to deep water off South Carolina. 



Considering the range in latitude alone, it is questionable whether we may fairly 

 assign either of these species to the "northern" group. In both cases, however, it is 

 possible that their occurrence in southern waters is restricted to considerable depths. 



Two other species (not plotted) which were taken by us only at the open ends of 

 Vineyard Sound and Buzzards Bay and at Crab Ledge are Hyas coarctatus and Pandalus 

 leptocerus. These may, perhaps, be regarded as predominantly northern species, though 

 they are recorded (depth not stated) for points far to the southward on our coast. 



Species which seem to avoid the colder waters, though elsewhere of general occurrence. 



Pagurus annulipes Nantucket Sound to Indian River, Fla. 



Pelia mutica Vineyard Sound to West Florida. 



Neopanope texana sayi Provincetown to East Florida. 



Another species, Pagurus pollicaris, might perhaps be added to this list. This 

 hermit crab, it will be seen, was not recorded from the stations at the extreme western 

 end of Vineyard Sound, though elsewhere prevalent. The case is not so striking, how- 

 ever, as those mentioned previously. The range of this latter species is said to extend 

 from Cape Cod Bay to South Carolina. 



None of these four species are recorded by us from Crab Ledge. All show, or appear 

 to show, an avoidance of the coldest waters of Vineyard Sound, and all are predomi- 

 nantly southern in their distribution upon our coast. It seems quite likely, therefore, 

 that temperature has been the factor responsible for the peculiarities in their local 

 distribution. 



Mention may appropriately be made here of certain species from southern waters 

 which do not properly belong to our local fauna at all. Among these are four crabs 

 {Planes minutus, Portunus sayi, Portunus ordwayi, and Arenceus cribrarius) and two 

 shrimps (Pcnceus brasiliensis and Latreutes ensiferus). In nearly all cases these species 

 have been found upon the floating gulfweed {Sargassum bacciferum), which is the home 

 of so many waifs from the far south. 



On the other hand, several shrimps of the genus Spirontocaris, which are known to 

 be representatives of a northern fauna, have only been taken from the outlying colder 

 waters of the region. 



Very few species among those dredged by us showed any evident restrictions as to 

 depth. This statement does not hold, however, for Ovalipes ocellatus, Cancer borealis, 

 and Pagurus acadianus. All of these were dredged most frequently at depths of 10 

 fathoms or more, despite the comparatively small number of dredging stations at which 

 such depths were recorded. Ovalipes, as we have seen, is by no means to be regarded 

 as a deep-water crab, since it is known to be common on sand flats in shallow water. 

 The greater average depth of the stations from which it was recorded results from its 



