I MATTHEW] STUDIES ON CAMBRIAN FAUNAS 17S 



from that species in the general form of the glabella and in the surface 

 markings. It might, when imperfectly exposed in the matrix, be mis- 

 taken for C. variolaris, Salt., of the P. Davidis zone in Wales. 



This is, perhajis, the latest of the Conocoryphea, and is not only 

 -dwarfed, but possessed a protective armature unknown in any of the 

 earlier species, viz.. the projecting anterior spine. A similar protective 

 process is found in two species of the next sub-fauna of the St. John 

 Gi-oup, viz., Anomocare stenotoides (in the young) and A. (Olenus ?) 

 spinosus (in the adult), and becomes common in certain trilobites of the 

 Ordovician system (Ampyx, etc.) 



PARADOX I DES, Brongniart. 

 Paradoxides Abenacus, mut. (PI. I., Hgs, 9a to c.) 



Paradoxales Abenacus. Trail. Roy. Soc. Can., vol. Hi., pt. iv., p. 78, pi. vii., fig.s. 



lia to (J. 



A form which, on account of the narrow free cheek and short pos- 

 terior extension of the dorsal suture, we refer to this species rather than 

 P. Tessini or P. Bohémiens occurs in the calcareous bands of the gray 

 îslate. The tixed cheek is narrower than in the type, which is found in 

 the horizon, iJiv. Id in the St. John basin, and the posterior extension of 

 the dorsal suture is unusually short. 



Sculpture. — The test is smooth, except for small scattered tubercles, 

 visible only with a strong lens. The fixed cheek is not wrinkled, as in P. 

 Abenacus type. A fragment of the hypostome shows strongly marked 

 raised lines, about 2 or 3 in the space of one millimetre, on the anterior 

 lobe, and less prominent and more distant raised lines on the anterior 

 marginal fold. The pleura' and rings of the thorax seenx quite smooth. 



Horizon, as stated above. 



Form -1. (PI. II., Hgs. \a to d.) 



A somewhat ditferent variety occurs in the black siliceous shales. It 

 has a broader and shorter tixed cheek. The test is thin and wrinkled and 

 freely studded with tubercles, which are larger than those of the preced- 

 ing form, and thus simulate the ornamentation of P. Forehanimeri of the 

 Andrarum limestone ; but if Angelin's figure of this species is correct 

 this form cannot belong to P. Forchammeri, owing to differences in the 

 dorsal suture, movable cheek, etc. 



The interi'upted thread-like ridges which are found on the front 

 slopes of the glabella are more obscure than in P. Abenacus type, and 

 the eyelobe and fixed cheek are smaller. The last segment of the thorax 



