76 DE. H. WOODWARD 02T THE DISCOVEEY OP TEILOBITES 



also SO good as to look at the specimens, and considered their litho- 

 logical character superficially to agree with the other rock-specimens 

 of the slate sent up by Prof. Dobbie from the same bed. Lastly, 

 Dr. Hicks, F.R.S., has seen and examined the specimens, and is quite 

 satisfied with their genuineness, and also with my determination of 

 the genus. 



The surface of the fossil is covered with minute chlorite grains, aU 

 slightly drawn out, in the direction of the squeeze, along the 

 friction-plane. 



Description of tlie Specimens. — The specimen from Bethesda *, 

 found by Messrs. Jones and Lloyd on 9th April 1887, exhibits on 

 two slabs the impression and counterpart of a Trilobite, which, 

 when perfect, measured about 3 inches in length, and about 11- 

 inch in breadth (see PI. IV. fig. 1). 



The relievo side is only 2|- inches long, the hinder inch having 

 been lost in breaking the slate ; but the intaglio, although injured 

 along the side, gives us, as nearly as possible, the entire length of 

 the whole body. 



The head, which is the widest part of the animal, is If inch in 

 breadth by 1| inch in length; the length has, perhaps, been 

 slightly increased by squeezing along the long axis of the specimen. 



The glabella is elevated and rounded in front : it is seven lines 

 broad, and above the neck-farrow it is marked by three lateral 

 furrows, the first or basal furrow actually crossing the glabella, and 

 the middle and frontal furrows being each rather deeply marked and 

 inclined somewhat backwards. The sides of the glabella are nearly 

 parallel ; it is 1| inch long, and in front of the central axial por- 

 tion, upon its fixed margin, is a small circiilar raised prominence. 

 The margin of the head-shield is rounded, and was marked by a 

 distinct rim, and circumscribed by a furrow within the border. The 

 cheeks are rounded and rather inflated. The posterior angles may 

 have been produced into a short spine, but it is not preserved in the 

 fossil before us. The facial suture appears to have run obliquely 

 across the cheeks and united with the glabella near the anterior 

 border, the eye (or rudimentary eye-spot) being near the centre of 

 the cheek ; the suture emerged on the frontal border nearly in a line 

 with the axial furrows. There are 14 free thoracic rings seen in 

 the counterpart. 



The axis is | inch broad at its widest part next the head, and 

 scarcely diminishes in breadth till near the pygidium, where it is 5 

 lines broad. Each segment of the axis appears to have been notched 

 on its posterior border. The thoracic rings measure 1^ inch across : 

 the pleurae are straight, the extremities rounded and facetted for 

 rolling up. 



The pygidium consists of about 3 coalesced segments ; but the ter- 

 mination is somewhat indistinct ; breadth 11 lines, length ^ inch. 



Of 25 genera of Trilobites met with from the Longmynds to the 



* Although the working is in the face of Bronllwyd, I do not think the 

 name is ever used except for the mass of grit above the quarry (J. Dobbie). 



