Vol. 58.] THE CAMBRIAN, EIC, OF THE MALVERN HILLS. 115 
tinguished by its smaller diameter; and from 0. corneolus by its 
greater length. The angle of divergence is smaller than in any of 
these forms, but not so small as in the American Hyolithellus. 
HYoLirHts MALVERNENSIS, sp. nov. (Figs. 10-15, p. 114.) 
Ty pe-specimen (fig. 10).—Shell straight ; length seen, 8 mm. ; 
breadth indicated, 3 mm.; angle of divergence of the sides near 
the apex = about 48°, decreasing to about 17° towards the mouth, 
average angle =about 22°. Ventral side uniformly convex, semi- 
circular in section; dorsal side gently convex, but becoming slightly 
flattened at the sides ; towards the apex uniformly convex ; lateral 
angles well-marked. Surface apparently showing faint traces of 
longitudinal and transverse lines on the dorsal side. ‘Taking the 
dorso-ventral diameter as unity, the remaining diameter is 1:69, 
or near the apex 1:9 mm. Mouth not preserved. Operculum un- 
known. . 
In a second fragment (fig. 14), measuring 2°5 mm. across ati the 
broader end, the angle of divergence is also about 22°; and ina 
third about 153°. In a fourth specimen (fig. 12) the width towards 
the mouth (3-75 mm.) is greater, the angle of divergence (about 
14°) is somewhat less, the convexity of the ventral side is more 
pronounced, and the transverse and longitudinal lines are distinct, 
both on the dorsal and ventral sides. [A fragment of a fifth specimen 
(M470), previously overlooked, is 5 mm. in length; the dorsal 
side alone is exposed. It measures 5 mm. in breadth towards 
the mouth, and the angle of divergence is 13°. <A portion of the 
external cast of this specimen clearly shows a series of closely-set, 
strongly-curving lines of growth, which indicate that the oral margin 
formed a prominent arch. A less distinct system of closely-set 
longitudinal lines is visible over the whole breadth of the shell.— 
January 11th, 1902. | 
The transverse sections vary somewhat in the different speci- 
mens, and in different parts of the same specimen. Taking the 
shorter diameter as unity, the longer measures 1:08 mm. and 1°68 
respectively (in the second and fourth specimens to which reference 
has been made). . 
The species is characterized among the Cambrian forms of 
Hyolithus by its large angle of divergence, but more particularly 
by its shape as seen in transverse section. It belongs evidently to 
Holm’s section ‘ Dorsi-lineati’ (H. Nathorstc, Holm) of the subgenus 
Hyolithus, hut ditfers from H. Nathorsti of the Lower Cambrian in 
the flattening of the lateral margins, and obviously also in the 
greater development of the longitudinal lines in the middle of the 
dorsal side. The curvature of the lines of growth on the dorsal side 
is about as great as in H. Nathorsti.} 
All the specimens were obtained from the Grey Hollybush Sand- 
stone of Raggedstone Hill (M 439, 443, & 470). 
* Holm, £verigcs Geol. Undersékn. ser. C, no. 112 (1898). 
12 
