ELONICHTHYS liGERTONI. 81 



those of the f.ice, thoiigli tlie iiiandible is certainly h)iigitu(linally striated ; a ridged 

 ornament characterises also the maxilla, as figured by Messrs. Hancock and Atthey 

 {op. cif., pi. XV, fig. 4), l)at the dental margin is tubercnlated. More than a dozen 

 laniary teeth can usually be counted, the largest attaining a length of 2^ inch, while, more 

 externally placed, are numerous teeth of a smaller size, all having the same conical sharp 

 and somewhat incurved form, with enamel cap on the tip. Similar teeth are found on 

 the dentary element of the mandible. Many specimens show that the branchial arches 

 were very well ossified ; one of them, now in the British Museum (Ward Coll.), is 

 figured on PI. II, fig. 8, of the present work. 



The scales are relatively of moderate size, nearly equilateral on the flank, and 

 showing the usual variations of size and shape on different parts of the body. The 

 exposed area is sculptured with very fine sharp, closely set ridges, which pass across 

 the surface from before backwards, ending on delicate denticulations of the hinder 

 border ; their direction is only very slightly oblique on the flank scales, though more so 

 on those further back, and they also frequently bifurcate or are intercalated. This 

 highly ornate sculpture persists all over the body, and it is likewise to be noted that the 

 large pre-anal scale is not concentrically striated, its ridges being more or less parallel 

 with the median keel-like elevation. 



The paired fins appear rather small; the five or six anterior rays of the pectoral are 

 unarticulated for about a third of their length. The dorsal fin commences opposite the 

 middle of the interval between the ventrala and the anal ; botli of these fins are rather 

 moderate in size, triangular-acuminate in form, and with the posterior border concavely 

 excavated. Their rays are proportionally rather coarse, their joints considerably longer 

 than broad in the front of the fin, but not so much so i)eliin(l ; their surfaces are striated 

 with fine ridges, which are sometimes longitudinal, sometimes oblique. The caudal is 

 large, deeply cleft and inequilobate. As is commonly the case in this genus, the rays of 

 the lower lobe have their articulations more distinct, and their surfaces more smooth 

 than those of the upper, in which the joints are shorter, and are striated just as in the 

 case of the dorsal and anal fins. 



Observations — '' Palceoniscus' Egertoni was originally named, but not described, by 

 Agassiz from isolated scales discovered in the coal shale at Silverdale, Staffordshire, l)y 

 Sir Philip Grey-Egerton, by whom a small specimen from the same locality was 

 subsequently described and figured in the Sixth Decade of the Geological Survey. The 

 mandible, maxilla, and teeth were in 1868 figured by Hancock and Atthey, from 

 specimens occurring in the Newcastle coal-field, and those two authors also pointed out 

 the correspondence between the microscopic structure of the teeth and those frum the 

 same coal-field named Ganacrodus hasttda by Sir Richard Owen,^ the same type of 

 structure having been long j)reviously figured by Agassiz in the Permian genus 



1 " On the Deutal Characters of Genera and Species, chiefly of Fishes from the Low Main Seam 

 and Shales of Coal, Northumberland,"' ' Trans. Odont. Soc. Great Britain,' vol. v, 1867, p. 349, pi. vi. 



