138 ilE. A. S. WOODWAED 03^ TWO GANOIDS EEOM EAELY MESOZOTC 



12. On tivo New Lepieotoib Gazs'oids from the Eaely Mesozoic 

 Deposits of Oeange Peee State, South Afeica. By A. Smith 

 WooDWAEE, Esq., E.G.S., E.Z.S., of the British Museum 

 (Natural History). (Read January 2b, 1888.) 

 [Plate VI.] 



The fine series of South- African fossils brought to the British 

 Museum in 1883 by Dr. Hugh Exton, E.Gr.S., Curator of the Bloem- 

 fontein Museum, Orange Eree State, has already furnished two im- 

 portant novel types of Yertebrata, made known at the meetings of 

 this Society by Professor Sir Eichard Owen *. There still remain, 

 however, other interesting forms, adding to our knowledge of the 

 palseontology of the early Mesozoic strata whence they were derived, 

 and among these are some beautifully preserved examples of a Lepi- 

 dotoid Ganoid fish. Two specimens of another new Ganoid have 

 also been lately received from the same source, and the affinities of 

 these types have so important a bearing upon the question of the 

 age of the Stormberg Beds of South Africa, that it seems advisable 

 to place on record their discovery and to offer a detailed description 

 of their characters. 



I. Semionotus capen^sis, sp. nov.t (PI. YI. figs. 1-5.) 



The first series of the fossil fishes in question comprises portions 

 of four individuals displayed upon the surface of a slab of sandstone, 

 mainly in counterpart. Each of these shows more or less of the 

 scaly trunk; and, in addition, one example exhibits the head, 

 pectoral fin, and dorsal fin ; another, the dorsal and caudal fins ; a 

 third, a nearly complete tail and the anal fin ; while the fourth is 

 almost perfect behind a point a little in advance of the pelvic fins. 

 There are thus materials for determining all the more salient 

 features of the fish, as illustrated in the accompanying figures. 



In general outline the body is eloD gated and fusiform, the greatest 

 depth being contained about three and a half times in the total 

 length, and the head occupies about one fourth of the whole. Both 

 the paired and median fins are well developed, the pelvic pair being 

 situated a little in advance of the opposing dorsal ; and all are cha- 

 racterized by the enormous proportions of the anterior fulcra. The 

 trunk is covered with rhomboidal scales of moderate size, and these 

 exhibit neither ornament nor marginal serrations. 



Head and Opercidar Fold. — The only specimen retaining the 

 head and opercular bones (fig. 2) is much crushed, but the outlines 

 of some of the elements are distinguishable, and, fortunately, these 

 can be studied in counterpart. Yiewed from the side, the roof 

 of the skull is seen to slope rapidly downwards from a position 

 somewhat in advance of the parieto-frontal suture, and the snout 

 was evidently acutely pointed. The parietals {par) and frontals (/r) 

 have been so displaced as to exhibit their shape and proportions, 



* Tritylodon Jongcsvus, Owen, Quart. Journ. Geol. Soc. vol. xl. (1884), 

 ]). 146, pi. vi., and Fihytidosteus ccqoensis, Owen, ibid. p. 333, pis. xvi., xvii. 



i- I'his fitb has already been quoted under the MS. name of Extonichthys, 

 Owen (J. Prestwich, 'Stratigr. Geol.' 1888, p. 18). 



