722 Davis — On the Fossil Fish-Eejnains of the Coal 3Ieasures of the British Islands. 



Dr. Anton Fritsch* discovered and described a number of similarly denti- 

 culated fossil remains attached to the gill-arches of Pleuracanths in the Gaskohle 

 of Bohemia. A comparison of the figures of the specimens described by 

 Dr. Fritsch with those now figured from the English Coal Measures will at once 

 demonstrate the identity of their origin and purpose. 



The specimen from the Lowmain coal seam at Newsham, represented on 

 PL Lxx., is the head of a large specimen, much crushed and displaced, but 

 exhibiting some interesting features. The mass preserved on the slab is 0"37 m. 

 from front to back, and 0-27 m. across the head. A large spine of Pleuracanthus 

 loBvissimus, Ag., extends from the centre of the slab, apparently the middle of the 

 head; it is 0-17m. in length, but the anterior part of the spine is absent. The 

 base of the spine, extending to the part on which the denticles are present, is 

 about O'lim. in length ; and had the whole of the spine been preserved, a com- 

 parison of this with other perfectly preserved specimens, indicates a length of 

 0-22 m. The base of the spine has a diameter of 0013 m., and higher, where the 

 denticulated surface begins, the diameter is 0"01 m. The surface of the spine 

 has the striated appearance characteristic of the species, and the denticles are 

 similar to those already described as P. Icevissimus. As to the manner in which 

 the spine was attached to the cranium, this specimen does not give much infor- 

 mation ; there are a number of semi-osseous structures in immediate proximity to 

 the base of the spine, and to these it may probably have been attached, but the 

 method of its attachment is not shown. 



Immediately below, and almost parallel with the spine, there extends the right 

 ramus of the lower jaw, crowded with teeth ; it originally extended beyond the 

 margin of the slab, but is imperfect. The teeth are similar to those exhibited on 

 PI. LXix., and are those known as Diplodus gibhosiis, Ag. The vertical arrange- 

 ment on the alveolar surface is well shown ; there were four teeth, possibly 

 more, in each row, which lie closely parallel to each other. Nineteen or twenty 

 vertical rows of teeth may be distinguished, and the extremity of the jaw 

 being absent the total number would be larger. Besides the teeth of this jaw, 

 there are numerous others scattered over the slab intermingled with masses of 

 bony structure representing the semi-osseous cranial plates. The latter are too 

 much disturbed to allow their relative natural position to be made out. 



The occurrence of the spine, Pleuracanthus Icevissimus, Ag., and the teeth, 

 Diplodus gihhosus, Ag., on this specimen is of importance, because it removes any 

 doubt as to the identity of the series of specimens obtained from the Lowmain 



coal seam. 



The specimen figured on PI. lxxi. is from the collection of W. Dinning, Esq., 



* Op. cit., p. 105, pi. Lxxx., figs. 1-12, &c. 



