20 BEITISH CAMBRIAN TRILOMTES. 



16. Agnostus securiger, sp. nuv. Plate II, fig. 11. 



This remarkable form, for the loan of which I am indebted to Prof. Lapworth, 

 is closely allied to A.integer, and may indeed be no more that a deformed specimen 

 of that species. 



It is rather larger than is usual in A. integer, but the head appears to show no 

 other difference. 



The most striking peculiarity is that the axis of the tail expands posteriorly 

 into ;i hatchet-shaped termination which occupies the whole of the posterior half 

 of the tail, exclusive of the margin. The lateral lobes are accordingly restricted 

 to a narrow space on each side of the axis in the front portion of the tail only ; and 

 each lateral lobe is marked by a median longitudinal furrow for about half of its 

 length. 



The specimen, however, is not perfect, and it is difficult to be certain that these 

 characters are not due to the mode of preservation. 



Head- and tail-shields, 5 mm. long, 5"5 mm. wide. 



Horizo?i a ml Locality. — (P Menevian) : Chapel End, near Nuneaton, " 40 feet 

 below unconformity." (Collected by Mr. Sykes.) 



17. Agnostus fallax, Linnarsson. Plate II, fig. 12. 



lsii'.i. Agnostus fallax, Linnarsson, Om Vestergotlands Cambriska och Siluriska aflagringar, Kong. 



Svensk. Vet. Akad. Handl., n. s., vol. viii, no. 2, p. 81, pi. ii, tigs. 54, 55. 

 1877. Agnostus fallax, Liimarsson, Geol. For. Stockh. Furh., vol. iii, p. 371, pi. xv, fig. 7. 

 1879. Agnosias fallax, Brogger, Nyt. Mag. for Naturv., vol. xxiv, p. 64, pi. vi, fig. 1. 



1879. Agnostus fallax, Linnarsson, Om faunan i kalken med Conocoryphe exsulans, p. 22, pi. ii, 

 fig. 33. 



1880. Agnostus fallax, Tullberg, Om Agnostus-arterna, p. 31, pi. ii, fig. 22 (forma typica), fig. 23a, b 

 (forma feroz), 



1896. Agnostus fallax, G. F. Matthew, Trans. N. Y. Acad. Sci., vol. xv, p. 214. 

 1902. Agnostus fallax, Gronwall, Bornholnis Paradoxideslag, p. 68. 



Head subquadrate, with a wide margin. Glabella bilobed, anterior lobe broad, 

 rounded in front; posterior lobe nearly parallel-sided, but slightly indented on 

 each side in front of the middle, with a small median tubercle; basal lobes large, 

 triangular. Axial furrows fairly deep. Cheeks confluent in front of the glabella, 

 widening slightly posteriorly. 



Head-shield 4 mm. long and wide. 



The width of the margin, the rounded anterior lobe of the glabella, and the 

 large basal lobes are sufficient to distinguish this form from any other British species 

 vel known. The head of J. exaratusis probably the form which is most likely to be 



