504 PROCEEDIlfGS OP THE GEOLOGICAL SOCLETT. [JuHG 17, 



not acuminate, is nevertheless more nearly so than in other Lepidoti, 

 and resembles in form and proportions that of Pacliycormus, another 

 Sauroid genus. The teeth are of two sizes, and constructed on the 

 same plan as the teeth of the undoubted Sauroids. The fins resemble 

 those of the Lepidoti in size, structure, and position ; but the tail is 

 more like that of a Eugnathus. The scales partake of both cha- 

 racters — those on the shoulders resembling Lepidotus, those on the 

 belly being lineolate, as in Eugnathus. The ornamentation of the 

 surface is generally regarded as only of specific value ; but on the 

 whole it is more like that of Eugnathus than that oi Lepidotus. I 

 am acquainted with several specimens of this form, some perfect, 

 some only fragmentary ; the latter were found arranged partly 

 with Eugnathus, partly with Lejndotus, until the discovery of a per- 

 fect specimen led to the recognition of their true nature. Lord 

 Enniskillen's best specimen measures 2 feet 2 inches in length, 

 without the tail, while my most perfect specimen measures 2 feet 

 within the same limits. The following table gives the comparative 

 measui'ements of the two specimens : — 



ft. in. ft. in. 



Length 2 2 2 



Head 7 7 



IS'ape to dorsal fin 7 8^ 



Dorsal fin 3^ 3^ 



Dorsal fin to tail 9 9 



TaiKimperfect) 4 . . . { ^PP-^l"^' } 5 



Dorsal to ventral fin. 9| 8 



Ventral to anal fin 4^ Wanting 



Anal to tail 7 Wanting 



Depth at shoulder 7i 6 



Depth at dorsal fin 7 



Depth behind dorsal fin 6 6 



Pedicle of tail 3 3 



Lower jaw 3 3^ 



Breadth of head 2^ 



These measurements correspond sufficiently to enable us to con- 

 sider the two specimens as belonging to the same species ; the de- 

 tails, therefore, will be taken from one or the other, according to 

 the state of preservation of the parts under description. A third spe- 

 cimen, belonging to Lord Enniskillen, is rather more slender than 

 either of those yielding the above dimensions. 



It will be seen from the Table given above that the head is about 

 one-fourth of the entire length, exclusive of the caudal fin. The 

 greatest depth of the body is at a point about halfway between the 

 occiput and the first ray of the dorsal fin, whence it decreases 

 gradually to the pedicle of the tail. The dorsal fin is situated over 

 the ventral fins ; it is preceded by five fulcral spines, and has mar- 

 ginal rays fringing the anterior edge of the fin; it comprises 

 twenty rays, the sixth being the longest, measuring about three inches 

 in length in one specimen, and four in the other. The pectoral fins 

 are long and broad, containing twenty rays each. The ventral and 

 anal fins are small. The component rays of all the fins are bifur- 



