76 ME. J. W. KIltKBY OX PERMIAK FISH AND PLANTS. 



Fam. 2. LEPIDOIDEL 



Pal^onisctjs yabjaxs, Kirhhy. PI. IX, fig. 2. 



Annals of Xat. Hist., 3rd Series, vol. IX, p. 267. 



The maximum length of this fish is from 3f to 4 inches. It 

 usually occurs much less, often being only If inch long. Its 

 maximum breadth is about an inch ; but this is a point subject to 

 much variation, the breadth of some specimens being one-third 

 of the entire length, and of others only one-fifth. The body con- 

 tinues of similar -width up to the dorsal and ventral fins ; it then 

 contracts somewhat rapidly to half the maximum width. The 

 head varies in length from one-third to two-sevenths of the 

 entire length, and its breadth is usually a little less than the 

 greatest width of the body. The tail is moderately but decidedly 

 heterocercal. 



The fins are of median size. The pectoral, which is about half 

 an inch long in mature examples, and placed at the junction of 

 the ventral and median thirds of the body, consists of from 18 to 

 20 slender rays, with one or more short but strong spine-like 

 rays in front. The ventrals are about iV inch shorter than the 

 pectorals, and placed If inch from the snout ; the rays are also 

 less in number, though stouter, than those of the pectorals. The 

 anal is 2^% inches from the snout ; or -^e inch behind the ventrals ; 

 it numbers from 8 to 10 jointed rays, which are stronger and 

 longer than those of the ventrals. The dorsal is placed about 

 midway between the ventrals and the anal or two inches from the 

 snout ; it is larger than the anal, being f inch long, and it has 

 from 10 to 12 jointed rays of similar strength to those of the anal. 

 In advance of the longest rays of the anal and dorsal are two or 

 three short, pointed, unarticulated rays ; one or two similar rays 

 are placed in front of the ventrals. The first segment of the artic- 

 ulate rays of the anal and dorsal is much longer than the suc- 

 ceeding segments — the succeeding segments being only about as 

 long as wide. Each ray is covered by long unsegmented scales 

 which usually hide from view the ray-structure. The front mar- 

 gin of each of these fins is protected by sharply pointed, linear 

 fulcral scales. The caudal is of moderate size and slightly forked? 



