93 



umbilical cavity, which is almost filled with the matrix), but the 

 ridge at the shoulder above is much more prominent and separated on 

 each side by a wider interval than any of the others, and the four which 

 surround the umbilicus are smaller than the three upper ones and placed 

 very close together. i 



Dimensions of the only specimen known to the writer : maximum 

 height, about ten millimetres ; greatest breadth, thirteen mm. 



Durham, J. Townsend, 1884 : a single specimen with most of the test 

 preserved. 



This little shell resembles Polytrojns Wisbyensis (the Oriostoma Wis- 

 hyense of Lindstrom*) from the Silurian rocks of Gotland, in so many 

 particulars, that it may ultimately prove to be only a geographical vari- 

 ety of that species. As far as can be ascertained at present, the princi- 

 pal difference between these two forms seems to be that on the umbilical 

 side of the Canadian shell there are at least five spiral ridges, which are 

 closely disposed and not very prominent, whereas on that side of the 

 shell in the Gotland species there are only two spiral ridges, which are 

 large and distant. 



CoDONOCHiLUS STEIATUS, Whiteaves. 



Codonocheilus striatum, Whiteaves. .1884. This volume, pt. 1, p. 17, pi. 3, fig. 3. 

 Codonochiliis striatiis, Fischer 1885. Man. de Conchyl., pp. 832-33. 



Hespeler, T. C. Weston, 1867, two specimens ; Durham, J. Townsend, 

 1878-8.5, abundant; Irvine Rocks, Elora, J. Townsend, 1885, three 

 large specimens. 



The systematic position of the genus Codonochilus is still uncertain, 

 though, as pointed out by Fischer (op. cit.) it is obviously most nearly 

 related to ScoUostoma, Braun. Zittel, in the second volume of his " Hand- 

 buch der Palseontologie," makes no mention of Codonochilus, but places 

 ScoUostoma in the family Soalariadse. Fischer, on the other hand, places 

 Codonochilus in the Delphinulidse, immediately after ScoUostoma and its 

 sub-genus Conchula, Steininger. 



Steaparollina Daphne, Billings. (Sp.) 



StraparoUus Daphne, Billings. .IS62. Geol. Surv. Canada, Pal. Foss. , vol. I., p. 



160, fig. 145. 



Gait, A. Murray, 1847, and R. Bell, 1861 ; Elo:-a, D. Boyle, 1880 ; 

 Durham, J. Townsend, 1878-82. 



*Silurian Gasteropoda and Pteropoda of Gotland, Stockholm, 1884, p. 167, pi. 17, figs. 

 26-28 and 45-46. 



