DEPOSITS or OllANGE FREE STATE, SOUTH AFRICA. 139 



and the former have about half the length of the latter ; the parie- 

 tals are united by an undulating median suture, and vary little in 

 width, but the frontals appear to taper considerably in front, and 

 their middle sutural line is almost straight, behind these elements 

 one of the supratemporal bones (st) is apparently recognizable ; but 

 in advance of the frontals nothing beyond crushed bone-fragments 

 can be seen, ^vith the remains of a terminal conical tooth. Of the 

 palato-pterygoid arcade there is an undeterminable fragment ; and 

 pertaining either to this or to the maxilla is a broken series of 

 powerful, hollow, conical teeth. A portion of the mandible (d) is 

 also observed, bearing traces of a similar dentition. 



The operculum (o/)) is of the form of a parallelogram, about once 

 and a half as deep as broad ; and the suboperculum (s.op), which 

 must have been scarcely half as large as the operculum, shows 

 the upwardly directed process of its antero-su])erior angle, so cha- 

 racteristic of the genus Lepidotus. In front of these bones there are 

 obscure remains of the preoperculum (j^.ojy), and immediately anterior 

 to this is a large superficial plate (^), situated between it and the 

 remains of the circumorbital ring. No traces of ornamentation are 

 visible, either on these elements or on the skull, unless a tubercle 

 upon one of the frontal bones is an indication of this character. 



Vertehral Column. — Nothing can be seen of the internal skeleton 

 of the trunk, with the exception of four of the hindermost haemapo- 

 physes of the vertebral column, which are widened distally for the 

 support of the caudal fin. There are no certain traces of ossified 

 ribs, though the fossils can hardly be regarded as sufficient to de- 

 monstrate the absence of these structures. 



Appendicular Skeletoji. — In the pectoral arch the clavicle (fig. 2, 

 cT) is well shown, of the ordinary Lepidotoid type ; and situated 

 posteriorly to the lower extremity of this is a small element {co.), 

 which may probably be interpreted as coracoid. The pectoral fin 

 consists of about 11 or 12 robust rays, which — as in all the other 

 fins except the caudal — are unarticulated for a considerable distance 

 proximaliy, though closely jointed nearer their extremities. The 

 anterior fulcra are destroyed, but they would probably be of enor- 

 mous size, like those of the other fins, this great development of 

 the fulcral scales being one of the most characteristic features of the 

 fish. The pelvic fins appear to have each comprised not more than 

 six rays, and these, as already stated, are placed slightly in advance 

 of the commencement of the opposing dorsal. 



In the dorscdfin the series of very large fulcra is succeeded by 

 at least 11 widely spaced rays, of which the anterior two are more 

 closely approximated than the remainder. The anal fin shows a 

 very strong interspinous bone supporting the fulcra, and there are 

 eight rays rapidly shortening behind. The atrophied upper lobe of 

 the tail is fringed above with fulcral scales, which diminish as they 

 extend upon the caudal fin ; and there are also well-developed fulcra 

 upon the inferior margin of the latter. This fin is symmetrical and 

 not forked, and the rays, in number about 14, are strong and closely 

 articulated from near the base, dichotomously branching distally. 



Scales. — The scales are strong and enamelled, varviug in form in 



l2 



