8 1 [AtwDod. 



sented on behalf of M. Elie de Beaumont, trro pamphlets on 

 his pentagonal system of mountain chains, taking occasion bv 

 the donation to urge on American Geologists the study of 

 Beaumont's system. 



Captain X. E. Atwood exhibited and presented the lower 

 jaw of a large shark, of which only one or two specimens 

 have hitherto been taken. One, obtained some years since, is 

 in the Museum of Comparative Zoology ; and another, taken 

 in the Gulf of Mexico, was given to the State Cabinet, and 

 the thu-d, captured at Provincetown, and now presente<i, 

 proved on comparison by himself with the one from the Gulf 

 of Mexico, to be the same, and an undescribed species of 

 Carcharias. 



In the stomach of this specimen, nearly the Trhole of a full grown 

 sword-fish was found, and some ten or twelve wounds in the skin of the 

 shark, giving evidence of the contest which must have occurred, and 

 establishing the identity of the victim. He suggested the specific name 

 of tigris as an appropriate designation for this shark when it should be 

 properly described. At present nothing could be said of the colors 

 and form of this shark other than that it was blue on the back and 

 white on the belly. 



Captain Atwood continued with some account of other sharks, pre- 

 senting the jaws of a male and female Dog-fish. {Mustelus cani^). This 

 shark, he observed, was the most common one upon our coast. He 

 had seen it at Gay Head. Martha's Vineyard, but knew nothing further 

 about its southerly limits. Both above and below Cape Cod it was 

 abundant, and was found all along the coast of Massachusetts. Maine, 

 Xova Scotia and the Gulf of St. Lawrence. He had never himseh* 

 seen them further north than the Magdalen Islands and the east coast 

 of Cape Breton Island, but reliable accounts say that it is found on 

 the southern coast of Xewfoimdland. 



As the Dog-fish appear at Provincetown a Httle while after the 

 mackerel, of which an accomit was given at a previous meeting, and 

 disappear shortly before them, he judged that they probably needed 

 warmer water than that fish, and therefore do not probably go quite 

 so far north. 



\Mien they first appear, they are in great abundance ; the females 

 alwap excel in numbers the males, but in the early part of the season 

 all are females, and all have young in some stages of development, 

 though not in every stage, there being seldom any between the young 

 just forming, and those nearly grown. The gravid females may be 



PROCEEDIXGS B. S. X. H.— VOL. X. 6 DZCZatBKB, lS6o. 



