STRUCTURE AND AFFINITIES OF THE PLATYSOMID2. 349 
a sufficient cause for removing it to the Pycnodont family.* The same circum- 
stance is also noted by Professor Youne, who mentions another specimen in 
the British Museum showing the palatal teeth in this genus, whose affinity to 
Mesolepis he fully recognises.t 
In 1867 I myself published a description of several of the bones of the head 
of Hurynotus,t including the operculars, maxilla, branchiostegal rays and tooth- 
bearing palatal plate, pointing out the presence of similar rounded teeth also on 
the edge of the maxilla. The restored figure of the side of the head which I 
gave at that time is, however, erroneous as regards the form of the snout, 
which, not having seen any perfect examples, I represented as forming a pro- 
jection over the mouth similar to that which is characteristic of the Paleonis- 
cidz ; the mandible is also too long and slender. Subsequent examination of 
a large quantity of additional material has, in other points, confirmed the 
observations then recorded. 
Species.—The species of Hurynotus require revision as regards their dis- 
tinctive characters, but this I must reserve for another occasion. I may, never- 
theless, here observe that, in my opinion, the fish in Lord ENNISKILLEN’s 
collection, which Sir Pattie Grey-EceErtoy§ referred to the Plectrolepis rugosus 
of Aaassiz, is a species of Hurynotus, and that the Platysomus declivus of 
AGassiz contained in Sir Pxrxip’s own cabinet, and catalogued by Morris,|| is 
most undoubtedly a distorted specimen of Hurynotus crenatus. For the oppor- 
tunity of examining both of these specimens I am indebted to the kindness of 
their distinguished owners. 
I am also indebted to the kindness and courtesy of the authorities of the 
Royal Museum of Natural History in Brussels for the opportunity of examining 
one of the specimens from the Carboniferous Limestone of Viesville in Belgium, 
recently described by Professor DE Koninck under the name of Platysomus 
(?) insignis. I find it to be an undoubted ELurynotus, and closely allied to 
E. crenatus of AGASSIZ. 
Geological Distribution.—So far as investigation has hitherto reached, the 
genus Hurynotus is confined to the Lower division of the Carboniferous forma- 
tion. In Scotland it ranges from the Wardie shales up to the top of the Car- 
boniferous Limestone series, and is especially abundant in Edinburghshire and 
Fifeshire; indeed, in the Calciferous Sandstone series of the latter county it 
seems to form the great majority of all the smaller fishes which the collector 
* On the Ganoidei Heterocerci, “Qu. Journ. Geol. Soc, Lond.” vi. 1850. 
+ On the Affinities of Platysomus and Allied Genera, “ Qu. Journ. Geol. Soc. Lond.” 1866. 
{ Description of Pygopterus Greenockii, &c., “ Trans. Roy. Soc. Edinb.” 1867. 
§ Ganoidei Heterocerci, p. 3. 
|| Catalogue of British Fossils, London, 1854, p. 339. 
{| Faune du Calcaire Carboniftre de la Belgique, in “Annales du Musée d'Histoire Naturelle de 
Belgique,” Brussels, 1878, p. 25, pl. iii. 
