May 25, 1906.] 



SCIENCE. 



821 



Various rounded and notably smooth pebbles 

 I observed wben making the latter portion of 

 the excavation from which I secured the type 

 specimen of Barosaurus, in the summer of 

 1898, now appear to indicate that gastroliths 

 accompanied that fossil, and it is very prob- 

 able that many instances of true gastroliths 

 have been overlooked. 



The lizards, as I have been shown by Mr. 

 A. Hermann, a most keenly observant lizard 

 fancier, swallow pebbles when feeding on a 

 pebbly cage floor; and he informs me that 

 some of his species swallow very large pebbles 

 for their size, these being soon passed. It can, 

 of course, be that such pebble-swallowing is 

 partly independent of stomach structure; but 

 in view of the fact that the Dinosaurs retained 

 and polished the pebbles, it is fair to assume 

 that their gastrolithic habit establishes the 

 presence of additional important structural 

 analogies with the birds. 



G. E. WlKLAND. 

 DEPOSIT OF VENUS SHELLS IN NEW YORK CITY. 



In excavating for the new building for the 

 United States Express Company, on Hector 

 Street, between Sixth and Ninth Avenue ele- 

 vated, Mr. Daniel E. Moran, C.E., found rest- 

 ing on the bed rock forty feet below the 

 surface a small deposit of Yenus shells, frag- 

 ments of wood and some peaty matter. This 

 deposit was covered by ten feet of glacial drift 

 which in turn was buried under thirty feet 

 of sand probably of post-glacial age. The 

 fossiliferous deposit was apparently protected 

 from the ice action in this spot by a local 

 ledge or shelf of the bed rock. 



The Venus shells resemble very closely those 

 of the recent F. mercenaria Linn, but differ 

 from them somewhat and along a line which 

 seemed to identify them with the variety 

 antiqua of Verrill from the Pleistocene de- 

 posits of Sankaty Head, Nantucket. The 

 Manhattan specimens were compared with a 

 number of these in the collections at Columbia 

 University and the identification was found 

 to be complete. The variety antiqua is an 

 unusually massive and strongly sculptured 

 variety. Professor Verrill's description being 

 as follows : 



The shell is rather obtusely rounded posteriorly 

 and is thickly covered with prominent concentric 

 lamelliform ridges, which mostly extend entirely 

 across the shell, but are often reflexed, appressed 

 and more or less confluent over the middle region, 

 where the ordinary variety is nearly smooth (ex- 

 cept when young). 



Professor Verrill mentions var. antiqua as 

 occurring in the ' lower shell bed ' at Sankaty 

 Head, but my work there in the summer of 

 1904 showed that the typical specimens occur 

 in the ' upper shell bed,' more nearly resem- 

 bling recent forms as the 'lower shell bed' is 

 reached.' 



The ' upper shell bed ' has a decidedly north- 

 ern fauna probably driven south by the ad- 

 vancing ice sheet, and as the recent form and 

 not antiqua is found in the lower beds con- 

 taining a fauna of rather southern range, it 

 seems as if antiqua is either a northern 

 variety or else has developed from the common 

 form as a result of the change to much colder 

 conditions. 



The identification of this V. mercenaria as 

 the var. antiqua of Verrill correlates this 

 Manhattan deposit with the upper beds at 

 Sankaty Head and indicates the existence of 

 these beds with their contained fauna as far 

 west and south as the neighborhood of New 

 York. 



The wood fragments were examined by Dr. 

 C. C. Curtis, of Colmnbia University, but the 

 original structure was so altered as to make 

 identification impossible beyond the fact that 

 they were from a deciduous tree. 



Some specimens of Ilyanassa ohsoleta Say 

 and an oyster fragment from the subway tun- 

 nel beneath the East River were recently re- 

 ceived at the university from Mr. J. F. San- 

 born. They were found 2,000 feet from the 

 Brooklyn side in the mud or silt thirty feet 

 below the bed of the river or seventy feet 

 below tide water, the river being here about 

 forty feet in depth. The oyster fragment is 

 probably from a specimen of our common 

 species Ostrea virginiana Lister, and the 

 Ilyanassa shells are apparently identical with 



- ' See ' Pleistocene Formations of Sankaty Head, 

 Nantucket,' Jour, of Geol., Vol. XIII., No. 8, 

 November-December, 1905, p. 728. ^ 



