297 



ment of the body chamber being ovate : venter narrower than the dorsum 

 and especially so at both ends ; lateral outline conical, with the ventral 

 border not much more convex than the dorsal. Septate portion occupy- 

 ing a little more than one-half the entire length, narrowly conical in 

 lateral aspect, pointed posteriorly and about twice as long as it is broad 

 anteriorly. Body chamber creaulated around the base, its outer margins 

 at first nearly straight and almost parallel on both sides as viewed late- 

 rally, its anterior termination rounded but much more broadly so on the 

 ventral side than on the dorsal ; ventral region at the summit laterally 

 compressed on each side of the aperture. Aperture, as viewed from 

 above, extremely contracted, Y-shaped, with the stem about twice as long 

 as either of the two branches, which diverge from it at an angle of about 

 115°, The stem is a narrow slit which expands at its outer termination 

 into a narrow and longitudinally elliptical orifice, exactly in a line with 

 the siphuncle, and the branches are similarly narrow divergent slits, 

 each of which widens into a smaller and circular orifice externally. 



" Surface markings consisting only, so far as known, of extremely fine 

 transverse striations, which are too minute to be shown in the figure. 



"Sutures slightly concave at the sides, closely approximated but rather 

 nearer together posteriorly than anteriorly ; siphuncle marginal and placed 

 in the median line of the venter. 



" Approximate dimensions of an average specimen (the one figured) : 

 entire length, thirty eight millimetres ; length of the septate portion 

 twenty one mm. ; greatest breadth, twelve mm. 



" Grand Rapids of the Saskatchewan below Old Portage, J. B. Tyrrell, 

 1890 : a number of casts of the interior of the shell, in a pale brownish 

 yellow or nearly white dolomitic limestone. 



"A singular little species, apparently well characterized by its diminutive 

 size, ovately conical, slender and nearly equilateral contour, as viewed 

 laterally, 'and by its narrowly contracted and widely divergent Y-shaped 

 aperture. It is not at all likely to be mistaken for any American species, 

 and is perhaps most nearly related to the G. clava of Barrande,* young 

 specimens of which have a very similar marginal outline. The aperture 

 of Q. clava, however, is regularly T-shaped at all stages of growth, and in 

 the adult stage it seems to differ very widely from the present species, 

 both in its dimensions and in its general contour." 



* Systems Silurien du Centre de la Boheme, Prague et Paris, tome II, 1865, pi. 77, figs. 



6-22, et pi. 92, figs. 10-13. 

 6. clava is from Etage E. of Bohemia, which is said to be the equivalent of the Lower 



Ludlow of England. 



