140 ME. A. S. WOODWAED ON TWO GANOIDS FEOM EAELT MESOZOIC 



different parts of the body in the nsual manner ; those of the middle 

 of the flank (fig. 4) are deeper than broad, gradually becoming rela- 

 tively less deep dorsally and ventrally (fig. 5), and passing behind 

 into the smaller rhomboidal lozenge-shaped scales of the caudal 

 pedicle. The posterior border is not in any case denticulated. 

 There is a slight median rib on the inner side of each scale, and on 

 the more anterior portion of the flank the ordinary peg-and-socket 

 articulation is observable. The " lateral line " is well marked, and 

 is very slightly arched upwards. 



Systematic Determination. — On consideration of the foregoing ana- 

 tomical details, it at once becomes evident that the South-African 

 fish is an ally of the widely distributed Mesozoic genera Lepidotus 

 and Seonionotus, if, indeed, it does not belong to one of the two. 

 The structure of the skull is essentially similar, and likewise the 

 form and proportions of the trunk and fins. The size of the fin- 

 fulcra is no greater than that of the fulcra met with in certain 

 species of Lejjidotiis (e. g. L. minoi\ Ag.) ; but the head in the j)re- 

 sent fossil is sufliciently well preserved to show that the dentition 

 was quite distinct from that of the last-named genus, and the scales 

 also evidently differ in the form of the overlapped margin. From 

 Semionotiis. however, no point of divergence of generic value is ap- 

 parently discoverable ; and the American species referred by Egerton 

 to IscJiypterus * (in allusion to the dimensions of their tin-fulcra) 

 seem to connect precisely the earlier recognized forms of the genus 

 with the new type here made known. The South-African fossil has 

 still larger fulcra even than the latter, and this character especially 

 serves to distinguish it from all the species hitherto defined. It 

 may therefore be appropriately termed Seinionotus caiiensis., as being 

 the first recorded example of this European and American early 

 Mesozoic genus occurring in the i^egion of the Cape. 



Formation and Locality. — Stormberg Beds (Upper Karoo Series) ; 

 the Drakensberg Eange, Orange Free State, South Africa t. 



* Sir Philip Egerton, quoted by Sir Charles Ljell, Quart. Journ. Geoi. See. 

 vol. iii. (1847), p. 277. As shown by Dr. Traquair's description (Quart. Joum. 

 Geol. Soc. vol. xxxiii, 1877, p. 559), I&chypterus presents no certain points of 

 difference from the typical species of Semionotiis "which can be regarded as of 

 generic yalue. The fin-fulcra are certainly larger than those of most forms 

 refei-red to the last-named genus ; but there are gradations between the ex- 

 tremes, and there appears to be an equal variation in the development of the 

 fulcra in the different species of the closely allied genus Lepidotus. 



t These particulars have been kindly furnished by Prof. T. Eupert Jones, 

 F.E.S., F.G.S., to whom T am indebted for the following information from the 

 ' Bloemfontein Gazette ' of July 5th, 1883, relating to the precise locality from 

 which the specimens of this fish were obtained. The fossiliferous bed occurs in 

 a precipice upon the farm of M. H. K. van der Merwe. about three-and-a-half 

 hours' march from Senekal, in the direction of Ficksburg. The precipice is 

 hollowed at the base by caves and rock-shelters, and the natives, who at present 

 use these as store-houses for their corn-baskets, first observed the fossil impres- 

 sions, pointing them out to the neighbouring farmers. " The late Mr. Stow 

 chisehed and split the portions of rock into fragments, and it seems probable 

 all available specimens have been removed till another slip of rock takes place." 

 In his ' Eeport of the Geol. Survey of the Orange Free State,' 1879, p. 48, 

 Mr. Stow remarks that " the fish are evidently new to science, but of an old- 

 world type, the scales being arranged in regular diagonal lines." The rocks at 

 the base of the precipice at Weltevredren are described by the same geologist 



