Yol. 67.] from: the pababoxides beds of comley. 293 



those just described. They are, however, too imperfect to admit of 

 exact identification. 



Except for the marginal rim, which at best is but poorly defined, 

 this form is very near to Ac/raulos quadrangularis (Whitfield), as 

 figured by Dr. Walcott. The eye-lobe in the Comley form is 

 possibly a little larger than that shown in his figure, and the 

 front is somewhat less distinctly rounded. The similarity in the 

 transverse view of the head with that of A. (?) Jwlocephalus is 

 very marked. 



Locality and horizon. — The upper section on the Shoot- 

 Hough Road, Comley ; from the ochreous band, about 4 feet below 

 the top of the Shoot-Rough-Road Flags. 



Ptychoparia Corda ; subgenus Liostracus Angelin. 



Mr. F. R. C. Reed, in his memoir on the Cambrian fossils of Spiti, 1 

 gives a valuable summary of the views expressed by various 

 authors on the classification of the many forms that have been 

 placed under the genera Ptychoparia, Liostracus, and Conocephalites, 

 and finally adopts these three names as subgeneric terms. 

 Pol] owing this arrangement, I place the three or four forms next 

 to be described under the subgenus Liostracus. 



Ptychopaeia (Liostracus) ptjlchella, sp. nov. (PL XXYI, figs. 

 1 a-2.) 



Craniditjm [353]: Size. — Moderate; length, exclusive of the 

 occipital spine = 8 millimetres ; width, across the eye-lobes = 

 9^ mm., across the posterior angles = 12 mm., in front of the 

 eyes = about 8 mm. 



General form. — Trapezoidal, with well-rounded front; all 

 features in strong relief. 



General convexity. — Considerable; about 1 : 4. 



Glabella. — Truncate-conical, with broadly round apex ; strongly 

 convex ; slightly curved longitudinally ; occupying about two-thirds 

 of the length of the head-shield, omitting the spine : width = 

 about a third of that across the eye-lobes ; without furrows. 



Occipital furrow. — Distinct; straight; not deep. 



Occipital ring. — Almost entirely merged into the base of a 

 sharp, pointed spine, which projects upwards and backwards, 

 reaches to a higher elevation than the glabella, and extends back to 

 a distance from the occipital furrow equal to about half the length 

 of the glabella. 



Axial furrow. — Wide ; and well marked, both at the sides and 

 at the apex of the glabella. 



Fixed cheeks. — Gently and evenly convex in cross-section; 

 most elevated about midway in the length of the head ; falling 

 steeply to the postero-lateral furrows and gently forwards ; con- 

 nected in advance of the glabella by the tumid part of the front. 



1 Pal. Indica, ser. xv, vol. vii, Mem. No. 1 (1910) pp. 13-18. 



