420 ME. F. E. COWPEE SEED ON THE [Aug. T896 



belong to Ch. Jceisleyensis, which is the common species, while 

 Ch. bimucronatus is very rare. Their characters appear to exactly 

 correspond with those of the latter species. 



Cheieuees cf. glaeee, Angel in. 



The single specimen in the Woodwardian Museum on which I rely 

 for this determination bears an exceedingly close resemblance to 

 Angelin's figure of Cluirurus glaber, Ang., 1 and I do not think it 

 justifiable to separate it without at any rate seeing Angelin's 

 figured specimen. Schmidt 2 also describes and figures a species of 

 Cheirurus which he compares with this species of Angelin's. 



There are no important points of difference between our Keisley 

 specimen and Angelin's species, as represented in his figure. The 

 Russian individuals do not appear to resemble Angelin's species 

 so closely. But in the presence of the pair of pits on the frontal 

 lobe we see a point of similarity between the Russian and English 

 individuals. 



Measurements. 



millim. 



Length of head-shield 23'0 



glabella , 165 



Width of do. at base 130 



„ „ „ across frontal lobes 16*5 



Length of frontal lobe 8'5 



Width of cheek (along posterior edge) 13*0 



Distance of eye from axal farrow 40 



„ ,, „ ,, posterior edge of cheek 60 



Cheieuees cf. clavieeons, Dalm. ? 



Portions of the glabella of a species of Cheirurus show a resem- 

 blance to Ch. clavifrons, but the fragmentary nature of our 

 specimens renders any precise determination impossible. 



Cheieuees (PseudosphjEeexoches) coneoemis, Angelin. 



Messrs. Marr and Nicholson 3 in 1888 recorded one species of 

 this subgenus from the Stockdale Shales and named it Ps. moroides. 

 Otherwise it has not previously been noticed in Britain. The 

 species Ch. (Ps.) conformis is a characteristic form of the Leptama- 

 Limestone of Dalecarlia, 4 and its occurrence at Keisley is another 

 important link in the chain of evidence connecting these two 

 limestone patches. 



Angelin 5 figures and describes the species, but imperfectly ; how- 

 ever, Schmidt 6 gives a full description and excellent illustrations in 



1 Angelin, « Paheont. Scandin.' 1854, pi. xxxix. fig. 16, p. 79. 



2 Fr. Schmidt, ' Rev. d. ostbalt. Silur. Trilob.' pt. i. p. 151, pi. vii. fig. 18 a & b, 

 Mem. Acad. Imp. Sci. St. Petersbourg, ser. 7, vol. xxx. (1881) no. 1. 



3 Quart. Journ. Geol. Soc. vol. xliv. (1888) p. 722, pi. xvi. figs. 9, 10 & 10 a. 



4 Tornquist, ' Undersokn. ofv. Siljansomradets Trilobitf'auna,' Sver. geol. 

 TJndersokn. 1884, p. 18, pi. i. fig. 12. 



5 Angelin, 'Palseont. Scandin.' 1854, p. 76, pi. xxxix. figs. 2, 2a. 



6 Schmidt, ' Rev. d. ostbalt. Silur. Trilob.' pt. i. p. 174, pi. x. figs. 5, 6 7, 9, 

 & pi. xvi. figs. 28-30, Mem. Acad. Imp. Sci. St. Petersb. ser. 7, voL xxx. (1881) 

 no. 1. 



