70 roNTRIBUTIONS TO CANADIAN PAL.KONTOLOOY. 



LeiiKlh of an average sized adult specimen, twenty-nine millimetres : 

 maximum bi'eadth of the same, fifteen mm,; length of the body whi)rl, 

 twenty. 



Belly IJiver, east side of Driftwood Bend, and Belly Eivev near its 

 Junction with the Bow Elver, G. M. Dawson, 1S81. South side of the 

 Milk Eiver, one mile above Pa-kow-ld Coulee and forty feet above the 

 water level, (^. M. Dawson, 18S1. South Saskatchewan, one mile 

 below tlie mouth of the Bow Eiiver, T. C. Weston, 18X3. Apparently 

 common at each ot these localities. 



At Driftwood Bend a numljor of s]iooimens were collected which 

 appear to be very young or half grown shells of this species. These 

 ditfer from adult or nearly adult examples in being narrowly fusiform, 

 with an attenuated and extremely slender spire not unlike that of an 

 Acella. (Jne of these, which is tigured on i)late 10, fig. 4c, and which 

 measui-es about ten millimetres in length, has as nuxny as seven V(.ila- 

 tions, the first three of which are exceedingly slender, fragile and 

 appai-ently non-persistent. The body whorl also of these half grown 

 shells is often eoncuvoly but shallowly constricted next to the suture. 



This shell is very doubtfully and only provisionally refei-red to 

 Meek's genus Rkyfophorus. It diffei-s mateilally from the two described 

 and typical sjjoeies (the H. priscus of Meek and the B. Mcehi of White) 

 in the total absence of the "small, oblique, shoi-t folds around the top of 

 the somewhat shouldere<l whorls" which suggesled the generic name and 

 which may or may not be an essential character. According to Meek* 

 " a slight eiirve in these little folds or eosta' indicates the presence oi' 

 a faint sinus in the lip near the suture, somewhat as in Sehizo.sfoiii.n, 

 Lea, but much loss deeply defined," and the type species is suid to 

 have ''one leather sti'Ong oblique fold" on the columella below, ''and a 

 much smaller less oblique one aljout half way up the aperture.' In 

 the present species there is a similar slight curve in the lines of gi-owth 

 next to the sutui'o, and a cori'ospondingly oblique fold in the columella 

 below, but the a])erture of all the specimens is so much filled u]3 with 

 the matrix that it is at present impossible to ascertain whethei- thei'e 

 was a second fold or not, without great risk of injury to the specime]is. 

 It may he that the present shell is moi'e nearly related to the South 

 American fresh water genus ChJ.Una than it is t(^ Bhytophorus. 



' li. .S. Geol. E.Npl. 40th Pariillel under Prof. (Jlarcncc King, vol. IV, p. 175. 



