from tlie Coal Meas^nres of Lancashire. 407 



Scmionotids. Farther study of tlic specimen, liowevcr, lius 

 shown that sucli a view is untenal)lc. The fisli certainly 

 exhibits a number oL' reniarkal)le characters, but in essentials 

 of structure it does not appear to have advanceil beyond 

 the stage of the contemporary Pala3oniscids. 



Both sides of the specimen seem, for the most part, to 

 present natural moulds of the outer surface, and for that 

 reason impressions taken from them are more intelligible 

 than the fossil itself. The accompanying figure has been 

 drawn chieiiy from such impressions. 



In general shape the fish is acutely fusiform, the snout 

 being produced and pointed, the head rapidly deepening pos- 

 teriorly, the back rising in a considerable arch behind the 

 head, and the body narrowing behind the dorsal and anal nns 

 to a comparatively slender tail-shaft. The line of the belly 

 from the shoulder-girdle to the anal fin is nearly straight. 

 The head is proportionately very large ; the measurement 

 from the point of the snout to the position that Avould be 

 occupied by the back of the opercular plates is one-third of 

 the total length to the base of the caudal fin ; and the head 

 was also very broad. 



I have asked Prof. D. i\I. S. Watson, who has made a 

 special study of the cranial structure of the Palseoniscidte, 

 to report on the head of this specimen, and I wdll here only 

 remark on a few outstanding points that appear in the figure. 

 The snout is produced in a roughly conical form in advance 

 of the mouth to a distance equal to half the length of the 

 mouth-opening ; the mouth-opening itself is very long and 

 straight as in the Pahieoniscids, and the bones forming it 

 appear also to be strictly of the Palseoniscid pattern. Tlie 

 maxilla, a narrow splint anteriorly, expands behind dorsally 

 into a large rounded plate with concentric strise ; its extreme 

 anterior point is slightly marked off from the rest and is 

 possibly a premaxilla. The lower jaw^ is incompletely shown, 

 but it is evidently narrow and practically straight. Part of 

 its length is well preserved, and bears sharply-maikcd 

 longitudinal striae. It also shows a perfect cast of a short 

 length of the mandibular sensory canal, with three of its 

 lateral tubules running out obliquely to the suifaee of 

 the jaw. The upper outline of the head from the snout 

 backwards is first markedly concave, then gently convex. A 

 conspicuous suture crossing the top of the head far back 

 probably separates the frontal and parietal; the small bone 

 behind it may be the whole of the parietal, and probably 

 much of the skull-roof in front of it is formed by the frontals. 

 The supratemporal is missing, unless it is to be recognised 



