92 CANADIAN MICRO-PALEONTOLOGY. 



p. 418, from the Wenlock Limestone of Beechey Island, is still more 

 like it, but has the normal sulcus instead of the central pit, and has not 

 so definite a marginal lip. 



The trivial name scitula will suit this pretty little Primitia. One 

 individual is attached to a specimen of Strophodonta demissa, and one 

 to an Orthis, from the Devonian rocks of the Hay Eiver (which runs 

 into Great Slave Lake), at about 40 miles above its mouth col- 

 lected by Mr. B. G. McConnell in 1887. 



3. ISOCHILINA BELLULA, (sp. nOV.). 



PL 11, figs. 16 a, 16 b. 



Length 1*0 (hinge-line '65), height "6, thickness '4 mm. 



Suboblong, upper and lower edges nearly straight, ends rounded, 

 front margin neatly curved, the hinder margin sloping down from the 

 back with an oblique curve. Surface smooth, with a mid-dorsal sub- 

 triangular depression ; the greatest convexity at the posterior third ; 

 marginal lip at the free edges. 



This is evidently allied to Isochilina Uneata, Jones (Quart. Journ. 

 Geol. Soc, vol. XLYI, 1890, p. 21, pi. ii, figs. 5 and 8), from the Hamil- 

 ton group at Monteith Point, Canandaigua, State of New York. 



This neat little form may well deserve the name Isochilina bellula 

 as a new species. 



One specimen was found attached to a Strophodonta demissa and 

 another to Atrypa reticularis ; both were collected by Mr. E. G. McCon- 

 nell in 1887, from the Devonian rocks of the Hay Eiver, Great Slave 

 Lake, at about 40 miles above its mouth. 



4. Isochilina Dawsoni, (sp. nov.) 



7 a 7 c 



7b 

 Fig. 7. Isochilina Dawsoni, sp. nov., a, left valve, cast; 6, edge view ; c, end view. 



Magnified 15 diameters. 



Size: Length 1*5 (hinge-line 1 -3) ; height 1*0; thicknes of carapace 



'QQ mm. 



Five specimens of a white polyzoan limestone, of Devonian age, were 



