JONES.] PALEOZOIC 08TRAC0DA. * 91 



1. Aparchites mitis, (sp. nov.). 



PI. 1], figs. 15 a&b. 



Length 1* (hinge-line -7), height -55, thickness •4 mm. 



Elongate-subovate. straight on the back, rounded behind, gently 

 curved on the ventral margin, obliquely curved at the antero-ventral 

 region, but with a fuller curve than the same edge has in Primitia 

 concinna *, Jones (Ann. Mag. Nat. Hist., ser. 3, vol. T, 1858, p. 249, pi. 

 X, figs. 3, 4, and vol. XYI, 1865, p. 424, and Geol. Surv. Canada, Org. 

 Rem., Dec. Ill, 1858, p. 99). The convexity also differs from the neatly 

 elliptical outline of the latter, and seems to be fuller at the anterior 

 moiety. 



The specimen before us having no trace of a sulcus or of a central 

 pit, nor of any overlap, must be taken as an Aparchites^ and may be 

 distinguished as A. mitis, sp. nov. 



Attached to a Spirifer-a disjuncta from the Devonian Eocks of Hay 

 River (Great Slave Lake), at about 40 miles above its mouth, collected 

 by Mr. R. (i. McConnell in 1887. 



This species, or one extremely like it, occurs in a grey, compact, 

 Devonian limestone from the Athabasca River. Collected by Mr. 

 McConnell in 1890. 



2. Primitia scitula, (sp. nov.). 

 PI. 11, figs. 14 a, 14 b. 



Length *77 (hinge-line '5), height -5, thickness '4 mm. 



This is a small Primitia, suboblong (short oblong with rounded ends) 

 straight on the dorsal, gently curved on the ventral edge ; anterior 

 extremity symmetrically rounded, and bordered with a flattened rim, 

 Postero-dorsal angle sufficiently pronounced to interfere with the 

 symmetiy of the hinder curve. Surface more convex behind than 

 before, bearing a central pit, and marked with a coarse and shallow 

 punctation. 



Primitia trigonalis, J. & H., Ann. Mag. Nat. Hist., ser. 3, vol. XYI; 

 1865, p. 421, pi. viii, fig. 4, from the Wenlock Limestone of Shropshire 

 exhibits some of the features seen in the form under notice, and P. 

 sigillata, J. op. cit., vol. I, 1858, p. 242, pi. ix, fig. 5, and vol. VI, 1865, 



* In the Quart. Journ. Geol. Soc, vol. XLVI, 1890, pp. 7-9, 1 have shown that this is probably 

 the same as d'Eichwald's Leperditia niinuta, and possibly equivalent to some of the spe- 

 cimens grouped under Dr. James Hall's Leperditia {[sochilina) cylindrica. 



