CYCLOPYGE BUMASTI. 19 



fauna, and this occurred in the "Whitehouse Beds ; but a complete, partially enrolled 

 individual in a fair state of preservation has recently been obtained by Mrs. Gray 

 from the Starfish Bed and shows some new features, since the hypostome and 

 epistome (= rostral shield) are in their natural position attached to the head. 



The epistome is subcrescentic in shape, widest across the middle, with obliquely 

 truncated lateral angles ; the posterior edge, which is somewhat chipped, does not 

 appear to have been arched back, for all the transverse striae arch gently forwards 

 concentric to the front margin ; these striae are numerous, regular, and equidistant. 

 The doublure of the head-shield is also concentrically striated, as Salter^ showed in 

 his figure, but he did not believe in the existence of an epistome, and held that 

 the facial sutures united marginally. The hypostome in our Girvan specimen is 

 large, convex and pear-shaped, extending nearly half the length of the head-shield ; 

 its anterior end is broad and gently arched forwards while posteriorly it tapers 

 rather rapidly to its blunt extremity, which reaches to the anterior end of the neck 

 of the glabella. The body of the hypostome is swollen, especially anteriorly, and 

 is transversely constricted at three-fourths of its length, where a pair of short 

 lateral furrows mark it. Fine concentric strige starting at right angles to the front 

 edge, ornament it. A pair of large triangular upturned alee not marked off by any 

 furrow from the body but similarly ornamented, lie at the anterior lateral angles of 

 the hypostome, and a narrow border encircles the body behind them. 



Salter's figure and description of the hypostome {op. cit.) were not complete. 

 The pygidium of our specimen shows a concentrically striated doublure of regular 

 width, extending inwards to the tip of the axis, as Olin- figured. 

 Dimensions. — 



Length of head-shield . . . 16"00 mm. 



Width of „ . . . . 23-00 „ 



Length of hypostome . . . 6*75 ,, 



Width of „ . . . . 6-00 „ 



Horizon and Localities. — (1) Whitehouse Group (M. Bala) : Whitehouse Bay. 

 (2) Starfish Bed, Drummuck Group : Thraive Glen. 



Genus CYCLOPYGE, Corda. 

 Cyclopyge bumasti, sp. nov. Plate III, fig. 8. 



Specific Characters. — Head-shield large, half the length of whole trilobite, convex 

 from side to side. Glabella subcylindrical, elongated, half the width of head, 

 (expanding a little in front so as to overhang eyes ?), unfurrowed, ornamented by a 

 few widely separated transverse gently arched strise. Eyes large, oblong, about 



1 Salter, 'Mem. Geol. Surv.,' dec. xi (1864), pi. ii, fig. 4. 



2 Olii], ' Chasmopskalken o. Trinucleusskiffern,' p. 64, pi. iii, fig. 10. 



