300 BRITISH GRAPTOLITES. 



The thecse are of the same general type as those of Cryptog. tricomis, but a 

 spine grows out from the lower end of the short free edge of each theca, and is 

 often so stont that when compressed it seems as if the denticle itself were drawn 

 out into a spine ; in less compressed examples, however, the true origin is clear. 

 These thecal spines may have a length of fully 2 mm., while those belonging to 

 th. I 1 and th. 1~ (the basal spines) are about 5 mm. long and are gracefully curved. 



The test appears to be attenuate, but to be thicker than in C. tricomis. 



Affinities. — C. Hopkinsou'i differs from Cryptog. tricomis in the greater length 

 of the curved basal spines, and in the fact that all the thecse have ventral spines ; 

 the polypary also is wider in proportion to its length. 



Horizon and Localities. — Middle and Upper Skiddaw Slates. 



Lake District : Outerside; Bannerdale Fell; Glenderamakin Valley. 



Associates, etc. — Cryptog. Hoplcinsoni has, up to the present, only been recorded 

 from the Skiddaw Series ; where it occurs associated with Tetrag. quadribrachiatus 

 in the Middle Skiddaw Slates and with Didymog. indentus in the Upper Skiddaw 

 Slates. It is not an abundant fossil. The type specimen is in the British 

 Museum Collection. 



Collections. — British Museum (Nat. Hist.) and Sedgwick Museum. 



Cryptograptus (?) antennarius (Hall). Plate XXXII, figs. 14 a — e. 



1865. Climacograptus antennarius, Hall, Grapt. Quebec Group, p. 112, pi. xviii, figs. 11 — 13. 



1868. Diplograpsus antennarius, Nicholson, Quart. Journ. Geol. Soc, vol. xxiv, p. 139. 



1870. Climacograptus antennarius, Nicholson, Ann. Mag. Nat. Hist. [4], vol. vi, p. 382, fig. 6. 



1898. Cryptograptus (?) antennarius, Elles, Quart. Journ. Geol. Soc, vol. liv, p. 519, fig. 31. 



1904. Climacograptus (?) antennarius, Ruedeuianu, Grapt. New York, pt. i, p. 721, pi. xvi, figs. 21 — 26. 



Polypary robust, 1*5 — 2*5 cm. in length, with an average uniform breadth of 



2 mm. Virgella small but usually conspicuous ; basal spines long, stiff. 



Thecce, ten to eleven in 10 mm., unknown except as sub-scalariform 



impressions or as crenulations of the ventral margin. 



Description. — All the British specimens of C. antennarius come from the 



Skiddaw Slates, and are badly preserved, so that the thecae are never well seen. 



The general form of the polypary, the sub-horizontal position of the basal spines, 



and the concealed thecae all point in the direction of Crypto grapt us, to which genus 



we believe the form belongs, though it may be a Climacograptus. 



The long basal spines form the most conspicuous characteristic of this species ; 

 as a rule, two only are seen, but not infrequently three are present, and it seems 

 almost certain that there were four, th. I 1 and th. I 2 each being furnished with 

 a pair. These spines are all stiff, approximately rigid, and fairly stout; they may 

 measure 8*7 mm. in length. 



