314 PROCEEDINGS OP TIIE ACADEMY OF 



or marbled, which may extend over the iliac region. Sometimes all the dark 

 markings are marbled with paler. There is a band on the front of the hu- 

 merus, and the hind limbs are frequently double-banded. 



Linee. 



From end of muzzle to cant bus oris 3-9 



" " to vent 12 



Length of fore limb 7'4 



" hind " 184 



" " foot 8-6 



Interorbital breadth 1'8 



Like capistrata, p alii at a, and the Eastern pickeringii, this is 

 one of the smallest species of the genus ; in form it is the. most distantly re- 

 moved from the typical forms, approaching distantly Chorophilus, which it 

 resembles in color. The lack of a vocal vesicle, not rarely occurring in the 

 genus Rana, I have not observed in any other species of this genus. 



No. 5293, 19 specimens (half rf), Cape St. Lucas. Jno. Xantus. 



November Qth. 

 Mr. Vaux, Vice-President, in the Chair. 



Thirty three members present. 



The followiug were offered for publication : 



" Fifth contribution to the Herpetology of Tropical America." By 

 Ed. D. Cope. " On the Habits of the Agricultural Ant of Texas." 

 By Gideon C. Lincecum. 



Dr. Hayden made some remarks in regard to an extensive chalk deposit on 

 the Missouri river. He also exhibited to the Academy some fossils, fishes and 

 shells, which had been taken from these chalk deposits by Mr. Geo. A. Prop- 

 per, a resident of Yankton, the capital of Dakota Territory. This formation 

 has been known for many years, and represents No. 3, or Niobrara group of the 

 Cretaceous series of this region. It commences at a point on the Missouri 

 river not far from Blackbird hill, overlapping, on the high hills, Nos. 1 and 2 

 of the Cretaceous series. Near the mouth of the Vermilion River it begins to 

 occupy the country, to the exclusion of any other rocks, and passes beneath 

 the bed of the Missouri near the Great Bend. It is thus visible for nearly 400 

 miles along the river. The fossils which have thus far been taken from this 

 bed are not numerous in species. The Ostrea congesta, Conrad, is perhaps the 

 most abundant shell. It is found in many localities aggregated in vast masses, 

 reminding one much of the little raccoon oyster that is left by the receding of 

 the tide along the shores of the sea islands of South Carolina. 



In< ceramus problematicus is abundant between Blackbird hill and mouth of 

 Big fr-ioux river. It is found in a grey, rather hard, chalk limestone, which 

 forms the base of the formation No. 3, and the rock is used much by the set- 

 tlers for building purposes and for burning into lime. I. p&eudomytiloide* and 

 /. cviculoides are found at different localities. This rock varies greatly in 

 eoler as well as texture, from a lead grey to milk white. It is oftener a deep 

 rust color, owing to the presence of the peroxide of iron. It resembles very 

 much our common chalk of commerce, and might be used for similar economi- 

 cal purposes. Although the organic remains thus far found in this formation 

 do not positively affirm it, yet there can be hardly a doubt that it is the Ame- 

 rica n representative of the white chalk beds of Europe. The fish remains are 

 mai y of them quite well preserved, and as they belong apparently to unde- 

 sci'bed species, they are placed in the collections of the Academy for future 

 study. 



[Nov. 



