CONTRIBUTIOXS TO CAXADIAS PAL.EONTOLOUY. 



Thaumastcs LDiiN^,i;iFnRJiis, Meek and Hayden 



Bidimii!<liimhviformis,Me&k a-iidllayden. 1856. Proc. Ac. Nat. Sc. Phil-, vol. 



VIII., p. 118. 

 BuUmuf! Xi'hraaons'is, jMeek and Hayden. lb. 

 TliaunvixtiM limnmfonms, IMeek. 1876. Ee]"). U. S. Geol. Surv. Terr., -^'ol. IX., p. 



553, pi. 44, figs. 8, a, b, c, d. 



South Saskatehcwan, six miles above the mouth of Bow Eiver and 

 thirty-five feet above the water level, G. 11. Daw.son, 1881 , one nearly 

 perfect specimen with the test preserved, and twelve casts of the 

 interior of the shell. 



The specimens from the "Western and Souris Eiver Laramie which 

 have been referred to T. I i'lmueifonnis on pages 20 and 27 have some- 

 times as many as seven volutions rather than " from five to six," though 

 in other respects they agree very well with Meek's description of that 

 •Species, e.specially in their polished surface which is said to be marked 

 only " by very fine, nearly obsolete lines of growth," in their mode- 

 rately elevated spire which is rejiresented as " a little obtuse at the 

 immediate apex,'' and in the flxct that their apertures and spires are 

 nearly equal in length. 



Premising that Thaumastm (Albers) is only a subgenus of BuUmuIus 

 (Leach) it is also to be noticed that the spires of such si^ecimens as 

 those figured on plate 3, whose nuclear whorls are exquisitel}' pre- 

 served, are miich more like those of many recent species of Bulimulus 

 from the West Indies and South America, when examined under a 

 lens, than they a:-e like those of any of the living species of Goniohasis. 



Dr. C. A. "White, to whom the originals of figures 3, 3a and 3b on 

 plate 3 wei-e submitted, was at one time inclined to think that they 

 should possibly be regarded as a variety of the Goniohads invenusta of 

 Meek and Hayden, but if that view be correct, then G. invenusta, as 

 suspected by Meek, can scai'cely be a true Goniohasis and probably not 

 even a fresh water shell. It maj^ lie that T. llmnceiformis, G. invenusta 

 and Limna'a comjmctilis, Meek, are more closely allied, both generically 

 and specifically, than their names would lead the student to suppose. 



The specimens collected by Dr. Dawson from the Belly Eiver Series 

 on the South Saskatchewan evidently belong to the same species as 

 those from the Western ami Souris Eiver Laramie, though those from 

 the first mentioned locality are a little larger and their spires are 

 rather more produced in proportion to the entire length of the shell. 



