PAL.KOZOIC MOLLUSCA. 243 



striae arched backwards to the band ; its spire is also shorter, and 

 there are no spiral ridges on the base. 



In the Upper Ludlow rock of Brigsteer, Kendal, Westmore- 

 land. 



{Col. University of Cambridge.) 



Murchisonia cancellatula (M'Coy). 



Desc. Conic ; apical angle about 50° ; spire of four whorls, ob- 

 tusely angalated a little below the middle ; the part above the 

 keel oblique, slightly convex near the sutures, slightly concave 

 near the keel ; portions below the keel convex ; body whorl of 

 moderate size ; base apparently imperforate (but imperfectly 

 seen) ; mouth obscurely rhomboidal, a little wider than high. 

 Length 1 inch 2 lines, proportional width j-^q, height of body- 

 whorl -f-^-^ ; entire surface above and below the keel reticulated 

 by nearly equal spiral and backward curved, oblique, trans- 

 verse sulci, eight or nine in one line. 



Mr. Salter, on a casual examination of some of our specimens 

 of this species, supposed them to belong to his Murchisonia sea- 

 laris (Geol. Journ. vol. v. t. 1. fig. 2), which he there says is a 

 common Bala species, recognized by its elongate shape, &c., and 

 imperfect specimens of the exterior of which he says show the 

 fine striae curving back to the keel ; but as the carinated species 

 I have seen from Bala are quite different from the present, and 

 agrde with the above figure in the elongate form, so diflPerent 

 from the present shell, which also has strong spiral strise, not 

 said to exist in the M. scalaris, nor in the Bala forms which I 

 have seen, I conceive this to be a perfectly distinct species. 



In the Upper Bala rock of A.llt yr Anker, Meifod, Mont- 

 gomeryshire ; abundant in the sandstone of Mullock quarry, 

 -Dalquorhan, near Girvan, Ayrshire. 



{Col. University of Cambridge.) 



Murchisonia gyrogonia (M^Coy). 



Desc. Acutely conical ; apical angle 45° j spire of three and a half 

 whorls, very strongly angulated in the middle by the pro- 

 jection of an acute carina, the upper and under sides of the 

 volution being flat and steeply inclined ; sutural angle 70^ to 

 75°; body-whorl rounded below, with an additional fine keel 

 about halfway between the principal one and the anterior end, 

 which is almost hid by the suture on the spiral whorls ; sur- 

 face (when preserved) marked with sharp strise, which, on the 

 upper part of the whorl, extend from the suture obliquely 



q2 



