22 



BEITISH FOSSILS. 



The animal is a little bent up towards the dorsal side. Its 

 length, measured in a straight line, is 47 in. ; the head is I'l in. 

 long, or, as in C. elegans^ rather more than one-fifth the whole body. 

 The front edge of the anterior dorsal fin {D) is distant 1'85 in. 

 from the end of the snout, and the base of this fin is 0*25 in. long. 

 From the front edge of the first dorsal to that of the second {D^) is 

 a distance of 0*95 hi. ; the base of the second is 0*2 in. long. The 

 front edge of the upper lobe of the caudal fin (C) is 0*7 in. from the 

 front edge of the second dorsal, and 3 -6 in. from the end of the 

 snout. Only the right pectoral fin, detached from the pectoral arch 

 and thrown backward, is visible. The two ventrals (F) close 

 together, and opposite the level of the posterior margin of the 

 anterior dorsal, are apparently in, or close to, their natural position ; 

 they are distant 2*35 in. from the snout. 



The small anal {A) is opposite the second dorsal, and 315 in. 

 from the snout. 



The greatest depth of the fish, 0*95 in., is opposite the first 

 dorsal fin. 



The pectoral fin (P) is rather more than 0'5 in, long, and 0*2 in. 

 broad at its base ; it is obtusely lobate, and contains, at fewest, 

 18 fin-rays. The foremost of these rays are unjointed through 

 the greater part of their length. 



The ventral fin (F) is 0*6 in. long and about 0-2 in. broad, or of 

 nearly the same size as the pectoral. It is obtusely lobate, and 17 

 or 18 fin-rays may be counted in it. As in the pectoral fin, the 

 foremost of these fin-rays are shorter than the others, and remain 

 undivided through a great part of their length. 



An impression of one, or both, of the pelvic bones (^Pv) lies in 

 front of the ventral fins, but apparently out of its normal position, 

 as its base is in advance of these fins. 



The anal fin (A) is somewhat bent upwards and backwards out 

 of its natural position. What there is of it has a length of 0*4 in., 

 a breadth at the base of 0*15 in. Fifteen or sixteen fin-rays may 

 be counted, and they appear to be similar in structure to those of 

 the pectoral and ventral fins. There is no evidence that this fin 

 was lobate. 



The base of the inferior lobe of the caudal fin (C) is 0-75 in. 

 long, and exhibits 14 fin-rays, the hindermost of which are nearly 

 parallel with the axis of the body, and probably indicate the 

 natural termination of the fin. The anterior are shorter than the 

 posterior fin-rays, and, so far as they are preserved, none of the 

 fin-rays exhibit distinct joints. 



The upper lobe of the caudal fin resembles the lower, and 

 begins opposite to, or perhaps a little in advance of it. 



The interspinous bones appear to correspond in number to the 

 fin-rays, (unless there may be one or two in front which have no 

 fin-rays,) and to be broader at each end than in the middle. 

 Opposite the anterior end of the caudal fin, the whole depth of the 

 body is about 0*65 in., and is divided into five nearly equal areas 

 by the impression of the notochord in the middle and those of 

 the vertebral arches and interspinous bones, above and below. 



