HEMIASPIS SALWEYI. 



179 





Species 3.— HEMIASPIS HORRIDUS :— H. Woodw. PL XXX, fig. 6. 



This species represented by a single example obtained by Charles Ketley, Esq., 

 from the Tunnel shale, Dudley, and now preserved in the British Museum is the oldest 

 example in time of this curious genus. 



When entire the carapace must have measured 1 \ inch in breadth by 8 lines in length j 

 the edge is thickly set with prominent sharp-pointed spines \ a line to a line in length, 

 whilst two strongly marked spines, 2 lines in length, project 

 from each posterior angle of the carapace ; the spines along 

 the hinder border of the shield, if present in this species, 

 are not preserved in this example. The median line of the 

 carapace, which is slightly tumid, is marked by one rounded 

 and prominent tubercle and two elongated confluent ones, 

 whilst on either side of this median line three other diver- 

 gent lines of elongated tubercles arise and radiate out- 

 wards to the border of the shield. The surface of the 



carapace between the tubercles is finely granulated, with here and there a slightly larger 

 pimple upon its surface. Eyes not visible. 



There are some other fragments which may indicate another species (see PL XXX, 

 fig. 3), but they are too fragmentary for determination, and I therefore think it best 

 merely to notice them in passing. 



Formation cindLocality . — Wenlock shale,Dudley. The specimen is in the British Museum. 



Fig. 69. — Head-shield of Hemiaspis 

 horridus, H. Woodward. (Re- 

 stored.) Wenlock shale, Tunnel, 

 Dudley. 



Species 4.— HEMIASPIS SALWEYI :— Salter. PL XXX, fig. 4. 



Limuloides tuberculatus, Salter, MS. (Mus. Pract. Geol.). 



Hemiaspis Salweyi, Salter. Lowry's Chart of Fossil Crustacea; Eurypterida, Fig. 3, 1865. 



This species is represented by two head-shields only; the body-segments, as with 

 the preceding species, are not preserved. The carapace, which is very tumid, is nearly 

 circular in outline, and measures 1-| inches in breadth and 1 inch in length. The 

 posterior border of the glabella is armed with two large spines, 3 lines in length and 4 

 lines apart, whilst three smaller ones, also directed backwards, are arranged on either 

 side of the genal border. The surface of the carapace is 

 covered with a minute granular ornamentation j the raised 

 central portion is flanked by a border of somewhat elon- I 

 gated tubercles j within the central area are three or four I 

 ronuded tubercles arranged in two oblique rows about four jL. 

 lines apart, commencing on the posterior border of the ^p^* 

 head at the base of the two large spines. One central pro- 

 minent tubercle and two lesser lateral ones on the front of FlG - ?o.— Head-shield of Hemiaspis 



Salweyi, Salter. (Restored.) U. 



the glabella, complete the ornamentation of the head-shield. Ludlow, near Ludlow. 



