THE GTJELPH FORMATION OF CANADA. 545 



Murchisonia tttreitifoemis, Hall. Plate XXYI. fig. 10. 



M. turritiformis, Hall, Pal. N. Y. vol. ii. p. 347, pi. lxxxiii, figs. 6 

 a. b. 



Spire long, turreted, many-whorled. Apical angle about 12°. 

 "Whorls increasing very slowly in size, their outer surfaces very 

 slightly convex or nearly flat, so that the two sides of the shell are 

 nearly parallel about its middle. Suture not deep. Well-preserved 

 specimens show a distinct spiral band a little below their centre. 

 Surface and aperture unknown. 



Nothing but fragments of this species have ever been described; and 

 all the specimens in my possession are imperfect. The shell must 

 have attained a considerable size, and probably possessed not less than 

 twelve or fifteen volutions. The species is nearly allied to M. Loganii, 

 Hall, from which it is distinguished by the much flatter whorls and 

 less deeply excavated suture. I have seen no examples showing the 

 interior ; but Hall states that the columella is of small size. The body- 

 whorl does not appear to have been ventricose ; and such specimens as 

 show portions of the actual shell would lead to the belief that the 

 surface was smooth. The carina, though not strongly elevated, is 

 generally easily recognized, and is usually placed decidedly below the 

 centre of the whorls. 



Formation and Locality. Guelph Limestones; Elora, Guelph, Gait, 

 &c, Western Ontario. 



Muechisonia macrospiea, Hall. Plate XXVI. fig. 9. 



M. macrospira, Hall, Pal. N. Y. vol ii. p. 346, pi. lxxxiii. fig. 5. 



" The specimen consists of the mould, showing the impression of 

 four and part of the fifth volution, marked by a strong carina along 

 the centre ; last volution showing a large canal extending downwards 

 in the direction of the spire. This species is larger and stronger than 

 the preceding" (i. e. M. Loganii). Hall, loc. cit. 



I am not aware that any other description than the above has ever 

 been published of M. macrospira, though the species is often quoted. 

 Prof. Hall's description, however, is taken from a single imperfect 

 example, and it is not sufficiently full to render identification easy. 

 The only specimen in my collection which I should be disposed to 

 regard as belonging to M. macrospira is a large fragment about three 

 inches in length, an inch and a half wide at the broken base, and half 

 an inch wide at the broken summit. The specimen exhibits six 

 whorls, the greater portion being hollow and exhibiting the interior 

 of the shell, whilst the remainder is occupied by the cast. The apical 

 angle is about 20° ; and the whorls rapidly increase in size from above 

 downwards. The columella is remarkably thick and strong, but is 

 simply rounded. The existence of a carina cannot be determined ; 

 and the specimen gives no information as to the characters of the sur- 

 face or the nature of body- whorl and aperture. 



If the above specimen be rightly identified with M. macrospira, 

 Hall, then the species is nearly allied M. Loganii, from which it 

 differs in its larger dimensions, and proportionally more rapid rate 



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