84 



from Gait, that is imperfect at the base. Not more than twenty-one 

 volutions can be counted in the most 'perfect specimen (from Elora) in 

 the Survey collection, but this specimen is imperfect at both ends. 



MUECHISONIA TUEEITIPOEMIS, Hall. 



Plate 12, fig. 4. 



Murchisonia turritiformis, Hall 1852. Pal. N. York, vol. 11. , p. 347, pi. 83, 



figs. 6, a-b. 

 Nicholson.... 1875. Rep. Pal. Prov. Ont., p. 70, pi. 3, 

 fig. 10.. 

 " " Whiteaves...l884. This volume, pt. 1, p. 26, pi. 4, 



fig. 5. 



Gait, A. Murray, 1847, and E. Billings, 1857 ; Elora, Dr. R. Bell, 1861 

 and D. Boyle, 1880; Hespeler, T. C. Weston, 1867 and 1871; Durham, 

 J. Townsend, 1874-82. 



The specimen represented on Plate 12, the test of which is beautifully 

 preserved on the seven later volutions, though the earlier ones are broken 

 off, was obtained by Mr. Townsend, in 1885, at the "cave," Irvine rocks, 

 Elora, and presented by him .to the Museum of the Survey. In this 

 specimen the volutions of the spire are laterally compressed, but most 

 prominent and obtusely sub-angular a little below the mid-height, where 

 they are encircled by a rather narrow and not much elevated spiral band, 

 which is flattened at the gummit and bounded above by a spiral impressed 

 line. The outer volution, which is not much larger than the one which 

 precedes it, and rounded below, is encircled by the spiral slit band a little 

 above the mid-height. On each of the volutions the numerous and close- 

 set strise of growth curve obliquely backward to the slit band above and 

 forward to the suture, on those of the spire, or to the base of the outer 

 volution, below. 



LoxoPLOCUS S0LUT?DS, Whiteaves. 



Plate 12, figs. 7 and 8. 



Murchisonia soluta, Whiteaves. ...... .1884. This volume, pt. 1, p. 28, pi. 4, figs. 



8 and 8 a. 

 Murchisonia tropidophora, Whiteaves. .1884. Ibid, p. 29, pi. 7, figs. 5 and 5 a. 

 Loxoplocus tropidophorus, Fischer 1885. Man. de Conchyl., etc., p. 847. 



The original description of M. soluta was based upon a number of casts- 

 of the interior of shells collected at Hespeler, Elora and Durham by 

 Messrs. Weston, Boyle and Townsend, which show only one spiral keel on 

 each volution. M. tropidophora, on the other hand, was described from 

 an imperfect specimen with nearly the whole of the test preserved, and 



