A. S. Woodivard — A Fossil Fish from the Purheck Beds. 401 



III. — A Description of Ceramuuus macrocephalus, a small Fossil 

 Fish from the Purbeck Beds of Wiltshire. 



By Arthtjk Smith Woodward, F.L.S., F.G.S., 

 Of the British Museum (Natui-al History). 



SINCE the publication of some notes on the English Purbeckinn 

 Fishes a few months ago,' the writei' has been favoured by 

 the Eev. P. B. Broflie, M.A., F.G.S., with the opportunity of re- 

 investigating and comparing the original specimen of the small 

 problematical fish Cernmiirus macrocephalus, briefly described by 

 Egerton* from the Purbeck Beds of the Vale of Wardour. Most 

 of the early descriptions of fossil fishes are inadequate for present 

 needs; and no genus and species could be less satisfactorily charac- 

 terized than that just referred to. A new attempt to elucidate the 

 fossil, in the light of modern knowledge, is thus very desirable, 

 more especially as no other specimens of the same fish have hitherto 

 been recognized. 



Egerton's original description, accompanying Brodie's figure, is 

 merely a brief note. He remarks that this little fish "presents the 

 nearest affinity to the remarkable genus Megnlums, but differs in 

 its slender iorm and the large proportional size of the head. The 

 vertebrge seem to be fewer in number, and of smaller diameter. 

 The most characteristic feature is the tail, which is strengthened 

 above and below by broad, elongated, fulcral scales. This interestino- 

 specimen may be designated by the name of Ceramurus, or tile-tail, 

 from the character of the fulcral scales supporting the lobes of the 

 caudal fin. The species may be called macrocephalus.'" Such is 

 the complete quotation, and no further particulars as to the genus 

 and species have hitherto been published. 



The fish in question is preserved in counterpart, but the head and 

 caudal fin are imperfect, w^hile a vein of calcite crosses it obliquely 

 at the hinder end of the abdominal region. There is also some 

 displacement at the back of the branchial region. The length of 

 the head w^ith opercular apparatus must have been about twice as 

 great as the maximum depth of the trunk, while it would probably 

 be contained four times in the total length of the fish. No feature 

 worthy of note can be observed in the fragments of the head. The 

 A'ertebral centra are delicate rings, which appear to have been disposed 

 in a spaced series so that in their crushed condition they are exposed 

 mostly in end-view. It is not possible to count them. The 

 neural arches in the abdominal region are much shorter than 

 their appended spines, which are loosely apposed apparently by 

 a forked base. The ribs are short, and especially delicate. The 

 neural and heemal spines in the caudal region are fused with their 

 respective arches, and these also probably with the vertebral centra. 

 The axis is much turned upwards at the base of the caudal fin, and 

 the haemal spines are thickened as usual. There are no traces of 



1 " A Contribution to Knowledge of the Fossil Fish Fauna of the English Purbeck 

 Beds," Geol. Mag., Dec. IV, Vol. II, p. 370 (April 1895). 



2 In P. B. Brodie's " Fossil Insects," p. 17, pi. i, fig. 2 (1845). 



DECADE IT. VOL. II. NO. IX. 26 



