CAMBRIAN ROCKS IN SOUTH SHROPSHIRE. 665 



length in front, to two thirds behind, with fulcrum at about one third 

 from the axis. 



Tail smooth; axis extending to two thirds the length, faintly 

 marked with transverse furrows; caudal fascia broad, well striated. 



This subgenus is distinguished by its large eyes and unforked 

 labrum. The central shield of the head is often found alone ; and its 

 peculiar shape is very distinctive. It is worth noting that both the 

 Asaphids of these ancient rocks have the labrum entire. 



Asaphtjs (PLATYr-ELTis) Croetii, Call. (Plate XXIV. fig. 2.) 



Asaplius (Platypeltis) Croftii, Call. Quart. Journ. Geol. Soc. vol. 

 xxx. p. 196, 1874. 



The characters of the genus will suffice for the one species. 



From the Shineton Shales at Shineton, where it is common ; Mary 

 Dingle, near Garmston ; Dictyonema-shales at Malvern (Dr. Grind- 

 rod's collection). 



Agjstostus, Bronyn. 



Agnosttjs dux, n. sp. (Plate XXIV. fig. 3.) 



Head: length and breadth equal, with a narrow margin; gla- 

 bella half the length of the head, sometimes longer, as broad as the 

 side cheeks behind, narrowing towards the front, with a transverse 

 sulcus one third from the front. 



Thorax : axis wide, each of its rings trilobed, the central lobe 

 much wider than the others ; pleurae not much longer than the side 

 lobes of the axis. 



Tail same size as the head, with small side angles ; axis one 

 half to two thirds the length of the tail, with a large tubercle at 

 each side in front, and a transverse sulcus about halfway down, the 

 triangular space thus enclosed rising into a tubercle. 



This species resembles A. Maccoyi, Salt., but differs from it in the 

 glabella, which in A. Maccoyi has its front division lunate, whereas 

 A. dux has the glabella divided transversely by a straight line, in 

 this respect resembling A. scutalis, Salt., and some other Menevian 

 forms. The largest specimen I have seen is a little over half an inch . 



From the Shineton Shales at Shineton. Not very rare. 



Conocoryphe, Corda. 

 Conocoryphe monile, Salt. (Plate XXIV. rigs, 4, 4 a, 4 6.) 



Conocoryphe monile, Salt. Cat. Cambr. & Sil. Foss. Univ. Cambr. 

 1873, p. 32. " Glabella lobed and front marginal furrow dotted." 



I add a fuller description of this interesting little species : — 



Oval, convex, surface finely granuliferous, length about \ inch. 



Head semicircular ; front marginal furrow dotted ; cheek-spines 

 long ; glabella strongly lobed, almost as in Calymene, three fifths the 

 length of the head ; facial suture cutting the front margin a little 

 inside the eye and the hinder margin a little inside the head-spines ; 

 eye large, placed near the side margin, ocular ridges well marked. 



