ee ee ea eS eee ee 
AND SUPPOSED EAR-BONES OF CTENODTS. 55 
in size, Mr. T. P. Barkas figuring whe in his “ Atlas of Carboni- 
ferous “Fossils” bee carteaecien 62 i inche in one pti aude and 54 
roopectirely. Mr. Atthe importa an operculum of C. elegans which 
is only 5-16ths of an inch in its longest diameter. I n my 
possession two Pe ema being 3} inches in its begets daunotag: 
and the other 2 ine The sizes of these opercula being so 
variable necessarily hindi us to infer that they pertain to different 
species of this genus, and in this conjecture we are strengthened 
by the facts that these bones vary also in their conformation and ~ 
thickness ; my observations tending to prove that the larger the 
operculum, the nearer it approaches to the circular form and the 
thicker is s the plate. The large opercle in my possession does not 
ear much 
he sa 2 
smaller one has a great similarity to the plate figured - Giint ther, 
* Philosophical Transactions” for 1871, pl. xxxv, fig. 
The literature concerning this bone is not lar rge, Mh 2. Es 
Barkas describing isolated specimens in the “ English Mechanic” 
and “ —— Opinion.” Messrs. Hancock and Att ey, in their 
paper on “ Dipterus and Ctenodus,” refer to it at some lengt 
and in the oat ail words: “The opercula resemble those of 
ipterus ; they are large, stout, slightly convex, irregularly cir- 
cular pla ates, with one side of the margin a little flattened; and 
Paired produced at each end of the flattened space ; the surface 
is punctate and granular like the cranial bones We possess six 
or eas different forms of th rs, two of which have 
been identified as belonging to C. elegans and C. obliquus respec- 
tively.” e only illustrations that have been publish 
y refe 
Before entering upon a description of the bones of the body of 
Ctenodus, I must refer to certain bodies that are supposed by Mr. 
ff ‘et Barkas to be otolites, and, as he considers probable, otolites of 
enodus. Concerning these bodies I do not feel in a position to 
commit myself to an opinion as to their nature, although I have 
xamined numbers of them alge externally and internally, as I 
have never had an opportunity of investigating the apes of 
an undoubted ear-bone of either a living or a fossil fish. — 
refore, allow rkas to speak in his own X wie, which 
from his “ Coal Measure -Palzontology 
“Fig. 175 represents a rare and little iets fossil, pro: 
lies eee otolite or ear ear-bone of a fish. Fig. 176, a 
anal In 
stediis ‘that Thad five specimens of this fossil, I said, ‘ In external 
appearance these specimens closely resemble each other, but, 
a 
