94 BULLETIN OF THE BUREAU OF FISHERIES. 



waters." Herdman records 58 species from the Irish Sea, while Graeffe lists 45 species 

 from the Gulf of Trieste. As implied in the foregoing discussion, it is likely that the 

 Woods Hole list will be greatly extended by further investigations. 



Referring to our dredging records for this group, the distributions of certain forms, 

 such as Cliona celata, Microciona prolifera, Tethya gravida, and Polymastia robusta, have 

 probably been ascertained with a fair degree of accuracy. On the other hand, it is 

 probable that some confusion occurs between the two species of Chalina, since specimens 

 which were listed in the field records as C. arbuscula were in a number of cases subse- 

 quently identified as C. oculata (see catalogue). For this reason a single chart has been 

 prepared, which includes all the records for this genus. A similar confusion exists 

 regarding the two species of Halichondria (H. panicea and H. caduca). And in addition 

 to these equivocal records specimens belonging to entirely undetermined species of 

 this genus are listed from about 20 of the regular dredging stations and were doubtless 

 taken at many others. 



Under such circumstances little of a general nature can be said regarding the 

 distribution of these animals in local waters. The species having the most general 

 occurrence was Cliona celata Grant (=Spongia sulphur ea Desor), which was recorded 

 from 171 of the regular stations. This form seems to flourish nearly as well on one 

 kind of bottom as another, though it is much less common in the western half of the 

 Sound than in the eastern half . b That its scarcity in the former region is not due to 

 the lower summer temperature of the water there is rendered probable by the fact that 

 this species has been reported by Lambe from Prince Edward Island, in the Gulf of 

 St. Lawrence. It has not been taken by us, however, at Crab Ledge, where many of 

 the typical cold-water species occur and many southern ones are lacking. 



Microciona prolifera is not uncommon in the Sound in the form of reddish incrus- 

 tations on the surface of stones and shells. In Buzzards Bay, particularly in the inshore 

 waters, it frequently grows up into the characteristic and beautiful arborescent form. 



A species of Grantia, which has been regarded as G. ciliata (Fabricius) by Verrill 

 and others, is common on piles, and one or more species of the same genus (not improb- 

 ably identical with the foregoing) were encountered at various points in dredging 

 (chart 10). 



An interesting case of restricted distribution is exemplified in the case of Polymastia 

 robusta, for which, however, no chart has been prepared, owing to the limited number of 

 stations from which it was recorded. This readily recognizable species was taken by 

 us a few times at the western entrance of Vineyard Sound and in the mouth of Buz- 

 zards Bay; likewise at five of the seven regular stations of the survey at Crab Ledge. 

 It is thus a representative of that colder water fauna which just enters the limits of our 

 region. So far as we know, this species has not been listed from points farther south 

 upon our coast than Marthas Vineyard, though ranging northward at least to the Gulf 

 of St. Lawrence. 



Another case of definitely restricted distribution, for which, however, no explanation 

 can be offered at present, is that of Tethya gravida. This species, which was first described 

 by Hyatt from specimens taken in Buzzards Bay, was encountered by us eight times, 



alt is stated by the authors that "the list is a very imperfect one, many common species not having been identified and 

 recorded." 



6 The chart lor this species likewise shows a considerable gap in the central region of the Bay. but specimens were later 

 taken at several points in this area. 



