Bevietcs — Dr. Traquair on Silurian Fishes. 



67 



■collectors from the Ludlow Bone-bed and the Upper Silurian 

 of Oesel. In shape the fossilized organism closely resembles 

 a Cephalaspis, and its anterior portion is usually crushed vertically, 

 while its slender caudal region occurs in more or less direct side 

 view. No orbits are distinguishable. There is no clear evidence 



Fig. 1. — Restored outline oi Lanarhia 

 spinosa, Traq., iu the jjosition in 

 which it occurs as a fossil, namely, 

 vertically compressed iu front, but 

 the tail twisted round so as to 

 appear in profile. 



of paired fins. The heterocercal caudal fin is well preserved, but 

 there is apparently no dorsal fin. Zanarhia is a new allied genus, 

 armoured with small, sharp, hollow, conical spines, instead of the 

 comparatively solid quadrangular tubercles. L. horrida, L. spinulosa, 

 and Z. spinosa (Fig. 1) are distinguished, the last with the dermal 

 spinelets not uniform in size. 



A remarkable new genus and species, Ateleaspis tessellata, follows 

 next. The remains on which it is based are rather fragmentary; 

 but Dr. Traquair is inclined to regard the organism as intermediate 

 between the simplest Heterostraci and the Osteostraci, only referring 

 it to the latter because part of the tissue of its armour exhibits true 

 bone-cells. The general form of the body is apparently as in the 

 Ooelolepidse, but the dermal covering in front consists of small 

 polygonal plates, while in the caudal region it is in the form of 



