584 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



Viviparns Raynoldsanus, M. & H. 



Plate 44, figs. 7, a, 1). 

 Vivipara Raynoldsana, Meek and Haydeu (1*61), Proceed. Acad. Nat. Sci. Pbilad., XIII, 446. 



Shell attaining a large size, rather thick ; spire elevated, and pointed at 

 the apex ; volutions about six and a half, increasing moderately in size, dis- 

 tinctly convex, but sometimes obscurely compressed around the middle, so 

 as to present a very slightly-shouldered appearance above ; last one prom- 

 inently rounded, or faintly subangular a little below the middle; suture deep, 

 owing to the convexity of the volutions, all the way up; aperture rounded- 

 subovate, a little>oblique; columella slightly perforated and regularly arcuate; 

 surface of upper volutions usually smooth, or only marked by very obscure 

 lines of growth, which generally become quite strong on the last whorl near 

 the aperture; while more or less distinct (in some examples well-defined) 

 revolving lines are also sometimes seen, two or three of which are stronger 

 than the others on the middle of the volutions, where they show a tendency 

 to develop into little ridges. 



Length of a large adult specimen, 1.60 inches; breadth of same, 1.15 

 inches; slopes of spire more or less convex, with a divergence from the apex 

 of about 60° to 65°. 



This is a very fine species, readily distinguished from all of the other 

 Upper Missouri forms. It perhaps more nearly resembles V. Leai, than any 

 of the others from that region, but differs in its larger size, proportionally 

 greater thickness, more produced spire, and more convex volutions, as well as 

 by its revolving lines, which show a tendency to develop into ridges. This 

 latter character, however, is not near so well defined on our figured specimen 

 as on some of the others. 



Among recent species, this shell seems to be most nearly related to V. 

 multicarinata, Haldeman (— V. carinata, Valenciennes), which was origin- 

 ally supposed to occur in Mexico, I believe. Mr. Binney, however, states 

 that he saw Valenciennes's type-specimen in Paris, with a label in that 

 author's own handwriting, saying that it came from the Philippines. His 

 figure represents a shell very similar to some of the specimens of the farm 

 under consideration, that have three or four of the revolving lines developed 

 into little ridges, or carinas. Our species, however, seems to have its spire 

 nearly always more elevated, and composed of one more volution, while its 

 revolving markings are usually more obscure. 



