WHITEAVES.] DEVONIAN FOSSILS, MACKENZIE RIVER BASIN. 225 



Dimensions of the specimen figured : lengtii, as measured in the 

 centre, thirteen millimetres and a half; maximum breadth, fifteen 

 mm. ; greatest height or depth of the closed valves, nine mm. • width 

 of mesial sinus at the front margin, six mm. 



Athabasca Eiver,^first ten miles below the mouth of the Clear 

 Water, Dr. R. Bell, 1882, — and opposite La Saline, twenty-tive miles 

 below the mouth of the Clear Water, R. G. McConnell, ]890 : one per- 

 fect and well preserved specimen from each of these localities. 



These seem to represent a mere local variety of S. tullia, in which 

 the beak of the ventral valve is much less arched and hooked than it 

 is in the typical form, and the number of ribs or plications on each 

 side of the mesial fold and sinus is much smaller. Prof H. S. Williams, 

 who has kindly compared both of the specimens from the Athabasca 

 with authentic samples of S. tullia, says that, in addition to these dif- 

 ferences, the area of the ventral valve in the former is proportionately 

 flatter and higher, and the finer surface strife are decidedly coarser than 

 in S. tullia. 



Subgenus JIartinia, McCoy. 



Spirifera (M.) glabra, var. Franklini. 



Spirifer {Martini a) Franklini, ^leek. 1868. Trtins. Chicago Ac. jSc, vol. 1, p. 107, 

 pi. xiv, flgs, 12a-c. For a list of the synonyms of 8 glabra, 

 ilartin, see Davidson's Mon. Brit. Carbon. Brach., p. 62. 



Hay Elver, forty miles above its mouth, E. G. McConnell, 1887 : one 

 rather small but nearly perfect specimen. Mackenzie Eiver, at the 

 " Eamparts," E. G. McConnell, 1888: one large and perfect specimen 

 and a detached ventral valve of another. 



The specific identity of the S. Franklini, Meek, with the S. glabra of 

 Martin (the type of McCoy's subgenus Martinia^ was first suggested by 

 Mr. C. D. Walcott in 1884, in his "Paleontology of the Eureka district 

 of Nevada." On page 139 of that monograph, under the heading Sp. 

 (M.) glabra, Mr. Walcott makes the following remark : — " Spirifera (M.) 

 Franklini, Meek," * * * " is, as mentioned by Mr. Meek, closely 

 related to S. {M.) glabra, and with the original specimen before me to 

 compare with the Nevada shells and Mr. Davidson's figures of the 

 species, it scarcely appears to be more than a variety, if even that, of 

 ,S'. {M.) glabra." 



