part 4] CAMBRIAN HORIZONS OF COMLEY. 357 



It is somewhat elliptical in general outline : the conical dorsal 

 portion has a slight elevation, is marked by numerous fairly-strong 

 concentric and also radiating striae ; the ventral (upturned) portion 

 is set nearly at right angles to the dorsal, and rises above the 

 general plane of the plate to a height of about a third of the 

 dorsi-ventral diameter. The angle at the apex of the conical 

 portion is about 115°. 



Dimensions. — Dorsi-ventral diameter = 7'5 mm.; transverse 

 diameter = 9 mm. 



Locality and horizon. — Comley, Lower Cambrian; from the 

 JProtoleiius Limestone, horizon Ac. 



Sub-genus Orthotheca. 



Hyolithus (Orthotheca) bayonet Matthew. (PI. XXIV, 

 figs. 12-16.) 



Orthotheca bayonet Matthew, 1899, Bull. Nat. Hist. Soc. New Brunswick, xviii, 



p. 193 & pi. iii, figs. 1 n-1 e. 

 Orthotheca bayonet Matthew, 1899, Trans. Roy. Soc. Canada, ser. 2, vol. v, sect. 4,. 



p. 114 & pi. vii, rigs. 1 a-1 e. 



This species is of frequent occurrence at one horizon at Comley, 

 and is represented a little lower in the series by a variety or 

 mutation. 



The more typical forms agree in all respects with the two 

 descriptions given by Matthew, except that the rate of taper is 

 about 1 in 6, and not 1 in 5 or 1 in 4 as given for the Newfound- 

 land specimens, and that the ventral faces sometimes exhibit a few 

 longitudinal stria?. 



The declination of the orifice from the dorsal side to the ventral 

 angle is well shown (fig. 15), as is also the concave outline of the 

 dorsal lip (fig. 13). 



Locality and horizon. — Comley, Lower Cambrian; from the 

 _P rotolenus Limestone, Ac.. 



A variety which may be named striatus (fig. 11) has more 

 definite and regularly-arranged longitudinal stria, and the growth- 

 lines indicate that the declination of the aperture towards the 

 ventral angle was slighter. 



Locality and horizon. — Comley, Lower Cambrian; from the 

 Stroiuella Limestone, Ac 4 . 



Hyolithus (Orthotheca) compressus, sp. nov. (PI. XXIV, 

 figs. 17 a& 17 b.) 



Type and only specimen [225, 226]. 



Diagnosis. — Shell, a curved elongated pyramid, rate of taper 

 changing from 1 in 4 near the apex to 1 in 3 towards the aperture 

 (equivalent angles 14° & 19°). Dorsal and ventral sides indistin- 

 guishable. Section, an elongated ellipse, ratio of axes 1 to -33, 

 lateral angles well rounded. Shell-substance thin, bluish grey, 

 phosphatic (?). Surface: marked by transverse lines of growth, 



Q. J. G. S. No. 304. 2 c 



