330 
CROSSOPTEEYGII. 
tmnk affords evidence of two “lateral lines ” on each side, 
the upper arising near the superior border of the oper¬ 
culum, and the lower near the inferior extremity of the 
clavicular plate. Purchased , 1851. 
24839. Three imperfect young individuals, laterally compressed, 
associated upon one small slab ; Dura Den. The head 
and clavicular plate are in each case preserved, but the 
extremity of the tail is wanting and all the scales and 
bones are much abraded. So far as preserved, the bones 
of the head and opercular apparatus agree with those of 
No. 26117 5, and a marginal series of small conical teeth 
is seen in the jaws. One pelvic fin is shown, apparently 
displaying a trace of the lobation; the first dorsal occurs 
directly opposite to this; and the large second dorsal 
seems to arise somewhat behind the origin of the equally 
large anal. Purchased , 1850. 
24839 a. Several fragments of small individuals; Dura Den. 
Purchased , 1850. 
26122. Type specimen of Platygnathus jamesoni, Agassiz, being, as 
pointed out by Traquair ( [loc . cit. 1888), the caudal ex¬ 
tremity of a species of Holoptychius, and almost certainly 
referable to H. flemingi ; Dura Den. By Agassiz the 
second dorsal fin is described as the anal, while the true 
anal and the inferior lobe of the caudal are regarded as 
two dorsals or perhaps one large dorsal accidentally 
divided. Purchased , 1851. 
(Other remains of this species are associated with Phaneropleuvon 
andersoni, and catalogued on p. 247.) 
Scales of undetermined species of Holopty chius have been recorded 
from the Old Bed Sandstone of England 1 , and the following is a 
similar specimen:— 
P. 5327. Imperfect impression of small scale, in conglomerate; 
Tortworth, Gloucestershire. 
Presented by the Earl of Dude , 1887. 
1 R. I. Murchison, Silur. Syst. (1839), pp. 175, 601 (from Crickhowell); 
W. H. Bailv, Rep. Brit. Assoc. 1864 (1865), Trans. Sect., p. 49, and Geol. Mag. 
vol. i. (1864), p. 293. The so-called scales of Holoptychius from Devonshire 
described by J. Phillips (Palseoz. Foss. Cornwall, Devon, &c., 1841, p. 133, 
pi. lvii. figs. 256, 257) do not pertain to this genus. 
