TRANSACTIONS OF SECTION C. 343 



In his examination of the character of Ammonites planorbis and its aptychus, 

 he had obtained curious and interesting results. He had found animal matter in 

 the interior of the whorls of the shell, probably the equivalent of the siphuncular 

 membrane as seen in the upper lias specimens. This contains thousands of rounded 

 egg-like bodies in its substance. 



All these facts were scarcely consistent with the idea that the aptychus was 

 simply an operculum. He hoped to obtain further evidence before asserting posi- 

 tively that — possibly with the siphuncular tube — it is an ovarian sac, but the facts 

 he had already worked out he thinks tend to that conclusion. 



Notes on a Fossil Tree from the Upper Silurian of Ohio. 

 By E. W. Clatpole. 



9. On Ostracocanthus dilatatus, gen. et spec. nov. A fossil fish from the 

 Coal-measures S.E. of Halifax, in Yorkshire. By James W. Davis, 

 F.G.S. 1 



The fossil fish remains so named were found in association with Ganoid and 

 Elasmobranch fishes of the genera Megalichthys, Ehizodopsis, Ooelacanthus, and 

 Gyracanthus, Ctenacanthus, and Pleuracanthus and several others, in a bed of 

 cannel or stone coal, a few miles SE. of Halifax. This peculiar Ichthyodorulite 

 is nearly U inches long, and | inch broad at the base. From the base the diameter 

 diminishes" rapidly, and at i an inch from the apex it is only -15 of an inch. It 

 remains about the same to the apex and ends in a blunt point. The upper part 

 is smooth and covered with hard ganoine. The lower part is grooved longitudinally, 

 increasing by bifurcation towards the basal end. Extending from the base, there 

 is a mass of bony matter, joined to the spine ; this is produced into two or three 

 short denticles, it then becomes thinner, but again expands into a mass which may 

 very well have served as the base of a second spine, if one was present. The only 

 fossil spine bearing any resemblance to it is Byssacanthus of Agassiz. It is, how- 

 ever, only a superficial resemblance, and this one cannot be arranged under that 

 genus. It also exhibits great similarity to the spines of Ostracion cornutus, the 

 Trunk-fish, one of the Siluroid Teleosteans. Prof. Huxley has advanced several 

 reasons for considering the Old Red species, Ooceosteus, Pterichthys, &c. as nearly 

 related to the modern Siluroids. It appears probable that the present specimen 

 may be a representative of the Teleosteans during the coal period. It may be 

 premature, considering the fragmentary nature of the specimen, to express such 

 an opinion, but the spine and its attachments are so different to all other fossil 

 fish remains which have been found in this country that I venture to suggest that 

 such may be the case, and that further discoveries may place its relationship 

 beyond doubt. I suggest the name Ostracocanthus dilatatus, as expressing its 

 resemblance to that of Ostracion and indicating its wide and dilated base. 



SATURDAY, AUGUST 23, 1879. 



The following Papers and Report were read : — 



1. The Age of the Penine Chain. By E. Wilson, F.G.S. 



In this paper the author combated the generally accepted view _ of the post- 

 Permian origin of the Penine chain, and contended" for a pre-Permian upheaval. 



1 Published in the Proceedings of the Yorkshire Geol. and Polyt. Society, vol. vii. 

 part 2, 1879. 



