426 ME. F. K. COWPER EEED ON THE [Aug. 1 896, 



level of the less elevated neck-ring. There are two distinct pairs 

 of lateral lobes of very unequal size. Each of the lobes of the basal 

 pair is elliptical in shape, obliquely directed forward and outward, 

 and is separated from the median portion of the glabella by a strong 

 furrow. The middle pair of lateral lobes consists merely of two 

 small circular nodules situated rather more than halfway forward 

 towards the front end of the glabella. There are slight indications 

 of a first pair of lateral lobes. 



The inner portion of each fixed cheek rises into a semilunar 

 rounded ridge embracing the side of the basal and middle lobes of the 

 glabella, but not elevated to more than half the height of the basal 

 lobes and separated from them by the curved axal furrow. At the 

 posterior end of this rounded ridge, and slightly towards its outer 

 side, is a small oval nodule. The outer portion of the fixed cheek 

 is small and apparently flat, with its posterior margin curving back- 

 ward. The facial suture runs backward and obliquely outward 

 to the small rounded eye-lobe, and thence in the same direction to 

 the posterior margin of the head-shield so as to cut it at an angle of 

 about 45°. The eye is situated rather behind the middle of the 

 glabella, at the end of a low ridge which traverses the flat outer 

 portion of the fixed cheek with a slightly oblique course. 



At the base of the axal furrow on each side of the distinct neck- 

 furrow is a small rounded nodule lying behind the basal lobes of the 

 glabella. The neck-ring is rounded and rather wide for the size of 

 the head-shield, but apparently is not provided with an axal spine. 

 A narrow neck-segment is discernible behind the fixed cheek, and 

 by its backward curvature seems to indicate that the genal angles 

 were furnished with spines. The surface of the head-shield is finely 

 tuberculated. The free cheeks are unknown. 



millim. 



Length of middle shield 3'0 



Width of do. at base 5-0 



Greatest height (close to anterior end of glabella) 2'0 



Length of glabella 20 



Width of do. at base 1*5 



Barrande's species, Acidaspis minuta, from Etage E bears a close 

 resemblance to this Keisley form, but in the Bohemian species the 

 middle lateral lobes of the glabella are oval and much larger, and 

 are situated nearer the anterior end of the glabella. The species 

 described by Tornquist x as A. evoluta from the Leptama-Limestone 

 is closely allied, but it differs in the larger size of the second lateral 

 lobe, and the greater width of the glabella. The outer portion of 

 the fixed cheek and facial suture are moreover not figured. 



Acidaspis, sp. 



A fragment of the head-shield of an Acidaspis in the Carlisle 

 Museum shows some peculiar features, but it is not sufficiently well 

 preserved to enable us to assign it to any known species or to 



1 Tornquist, ' Uniersokn. ofv. Siljans. Trilob.' Sver. geol. Undersokn. 1881, 

 p. 28, pi. i. fig. 24. 



