Nicholson and Marr — On the Lake-district. 339 



by its sliorter and deeper body. Tn sliape and relative proportion it 

 resembles P. granulatus, and might be taken for its young form : 

 but the unornamented scales with entire margins preclude its being 

 referred to that species. The extreme length is 77 mm. (3 inches) 

 ,of which the head occupies the fourth part ; between the hinder 

 margin of the operculum and the insertion of the caudal fin the body 

 measures 40 mm., and the depth in front of the ventral fins is 25 mm. 

 The head is crushed, and but little of the external surfaces of the 

 bones are preserved. The orbits are not large, nor are any teeth 

 visible. There is not the slightest evidence by depression or other- 

 wise of the presence of the notochord. The fins appear to have 

 been small and the rays few. The insertion of the dorsal fin is a 

 little in advance of the opposite anal fin. Long acute imbricating 

 scales cover the front ray of both fins. The caudal fin is composed 

 of about 20 strong and jointed rays with several fulcral scales above 

 and below, and is not deeply cleft. The structure and general form, 

 of the scales are the same as in P. purbeclcensis ; namely, high and 

 narrow scales on the flanks, which gradually decrease posteriorly, 

 with small scales on the dorsal and abdominal regions. Most of 

 the larger scales are either wanting or broken ; but well-marked 

 impressions of the outer surfaces of those missing are preserved on 

 the matrix. On another fragment of a larger individual (B. M. 

 P 3607), the scales are in better position, and also show the inner 

 side. Both specimens are from the Upper Purbeck Beds at Upway, 

 near Weymouth ; and formed part of the Egerton and Enniskillen 

 -collections respectively. 



It is deserving of remark that Pholidophorus is found associated 

 with Lepidotus in many of the marine formations of the Jurassic 

 period, and also in the estuarine deposits of the Purbecks, proving 

 that species of both genera frequented estuarine waters. 



DESCEIPTION OF PLATE X. 



Fig. 1. PJiolidophoriis hrevis. British Museum (P 1074). 



„ 2. Fholidophorus purbeckensis, drawn from the two slahs in the British. 



Museum (40635). 

 „ 3. „ „ enlarged external view of the flank scales on 



Mr. Damon's specimen. 

 ,, 4. „ „ restored inner view of the same scales showing 



the medial ridge. 



II. — On the Ocourkence op a New Fossiliferous Horizon in 



THE OrDOVICIAN SeRIES OF THE LaKE-DiSTRIOT. 



By H. Alleyne Nicholson, M.D., D.Sc, F.G.S., and 

 John E. Makr, M.A., F.G.S. 



BELOW the " Coniston Limestone Series " — if we include under 

 this general title not only the Coniston Limestone proper, but 

 also the " Style End Grassing Beds " of Long Sleddale and the 

 " Dufton Shales " of the Cross Fell area — no fossiliferous beds have 

 hitherto been detected in the Lake-district till the horizon of the 

 Upper Skiddaw Slates (Llanvirn Series) is reached. Between these 

 two horizons are placed the thick and varied volcanic rocks which. 



