374 G. J. HINDE ON ANNELID JAWS FROM THE WENLOCK AND 



This species, in its elongated tubular form, differs considerably 

 from any other form of these jaws. It appears to be rare, as I have 

 found only a single specimen. 



Log. and form. "Wren's Nest, Dudley: Wenlock group. 



Genus Akabellites, Hinde, 1879. 



Aeabellitbs coenutus, Hinde. 



Arahellites cornutus, Hinde, Quart. Journ. Geol. Soc. vol. xxxv. 

 p. 377, plate xviii. figs. 13, 14, 15. 



This beautiful form occurs equally well preserved in the Silu- 

 rian rocks of England as in the Cambro-silurian of Canada. The 

 only variations that can be noticed are that the anterior hook is re- 

 latively more robust, and the smaller denticles are more acutely 

 pointed and slightly further apart from each other. There is more 

 uniformity in the dimensions of the English specimens, which average 

 1 J line in length and | line in width ; there are about 14 of the 

 smaller denticles, the last three being extremely minute. It is an 

 interesting fact that these "Wenlock specimens are identical with the 

 forms from the relatively older strata of the Cincinnati group of 

 Canada ; whilst the allied species A. elegans, from the contemporane- 

 ous or homotaxial Clinton group, does not appear to be represented in 

 the Wenlock strata. 



Log. and form. Much Wenlock : Wenlock group. 



Arabellites extensits, Hinde. (PI. XIV. fig. 12.) 



The main portion of the jaw formed of a relatively thick, some- 

 what concave plate with a prominent knuckle-shaped posterior ex- 

 tremity ; the basal margin is curved, with a stout sharp-pointed an- 

 terior hook oblique to the main portion ; the upper margin is prolonged 

 backwards to form an extended arm on which there is a series of 

 recurved denticles. The number of denticles altogether on the 

 upper margin is about 15. Length 1| line; width | line. 



The tooth-bearing extension renders this species very distinct 

 from any of the preceding. A form closely allied to, if not identical 

 with the present species also occurs in the Cincinnati group at 

 Toronto ; but the only example I have of it is not sufficiently perfect 

 to aUow of description. 



Log. and form. Much Wenlock; Iron Bridge: Wenlock group. 



Arabellites spicatus, Hinde. (PI. XIY. fig. 13.) 



Main portion of jaw subrhomboidal in form and concave, with an 

 elongated anterior hook, the extremity of v/hich is wanting in the 

 specimen ; the posterior extremity is hollowed out, and has an ele- 

 vated spike-like projection at the corner of the base ; the upper 

 margin is nearly straight and extended backwards beyond the main 

 portion of the jaw ; there are about 10 small denticles. The reverse 

 or inner side of the jaw shows a deep groove beneath the anterior 



