22 



TRILOBITES OF GIRVAN. 



Dimensions. — 













I 





II 



III 



Length of whole trilobite 



. 23-0 mm. 





— 



„ of head 



. 11-0 





. 22-0 mm. 





„ of thorax 



. 7-5 





— 



. 9-0 mm. 



of pygidium . 



. 4-5 







7-5 „ 



Width of glabella at base 



. 7-0 





. 12-0 mm. 





Maximum width of glabella 



. 9-0 





. 16-0 „ . 



— 



"Width of thorax at front end 



. 8-5 









,, of pygidium 



. 10-0 





— 



14*5 mm. 



,, of axis of ditto . 



. 2-5 









— 



Bemarls. — The shape of the glabella and the long spinose first pair of pleurae 

 necessitate the separation of this species from C. armata, Barr., to which it was 

 previously referred. The enormous eyes recall C. mirabilis (Forbes),^ but the 

 organ of sight is not bilobed in front. The pair of pits on the third axial ring of 

 the thorax recall G. jjvisca, Barr.,^ and G. binodosa, Salter.^ In G. prisca, Barr., 

 it is the last pair of pleurae which are produced into long spines ; and the head 

 of this species is quite distinct. The large pygidium* compared by me to G. 

 gigantea, Barr., may probably be referred to G. suharmata. 



Horvum and Localities. — Whitehouse Group (M. Bala): Whitehouse Bay; 

 Shalloch Mill. 



Genus BOHEMILLA, Barrande. 

 Bohemilla scotica, sp. nov. Plate IV, fig. 1. 



1904. BohemiUa sp., Reed, op. cit., pt. ii, p. 53, pi. viii, fig. 4. 



In the former specimens of Bohemilla from the Whitehouse Group, which were 

 fully described by me in 1904, no traces of a border or "fixed cheek" Avere 

 preserved, only the so-called glabella being known. But, in a beautiful example 

 recently obtained by Mrs. Gray from the same locality (Whitehouse Bay) and 

 horizon, there is seen to be present a narrow border, somewhat as represented in 

 Barrande's figure of B. siupenda,^ running round the front and sides of the first 

 segment (the so-called frontal lobe) as a depressed band and produced in front 

 into a small median point, while its posterior ends are slightly swollen ; a narrow 

 furrow marks off this border from the " glabella." 



^ Salter, ' Meui. Geol. Siu'v.,' dec. vii, p xl., figs. 1 — 7. 



2 Barrande, ' Syst. Sihir. Boheme,' vol. i, Suppl., p. 63, pi. v, figs. 1 — 7 ; pi. vii, figs. 19, 20; pi. 

 viii, figs. 5, 6. 



^ Salter, 'Mem. Geol. Surv.,' dec. xi, pi. iv, figs. 1 — 6. 



4 Eeed, ' Giivau Trilob.,' p. 163, pi. xx, fig. 5. 



5 Barrande, ' Syst. Silur. Bolieme,' Suppl i, Trilob. p. 137, pi. xiv, fig. 30. 



