REPORT ON FOSSIL FISHES. 43 
at all, save when the specimen is held in certain lights. The specimen being 
unique, we had as yet no means of comparing it with others. 
Lastly, as regards the Tarrasius, the specimen in question is also unique, 
in showing the head and anterior part of the body, and further, its obscuration 
by an irreparable film of matrix, renders accurate conclusions really unattain- 
able until better specimens be discovered. (See the descriptions of Holurus 
ischypterus and Tarrasius problematicus, at pages 66 and 64.) 
But in the case of Phanerosteon, no lateral body scales are seen on any of 
the specimens, four in number,* in which the body is shown, with the sole 
exception of a few immediately behind the shoulder girdle in one example. 
On the other hand, in all the three which exhibit the tail, the caudal body- 
prolongation is clothed with a set of scales, limited in the very same manner 
in each, and these are as well preserved and as strong as the scales of any 
other Paleoniscid from the same beds. Although the azygous scales in 
front of the dorsal fin are only shown in one example, their being detached 
from such a situation, if not connected with lateral ones, may be readily 
understood. 
If we then consider, finally, that all the other Palzeoniscidz which occur in 
the same beds along with the present species have their scales all over the 
body in an excellent state of preservation, the most obvious conclusion seems 
to be that, im this stance, lateral body scales were absent, excepting a few 
immediately behind the shoulder girdle ; the only other alternative being to 
suppose that they were, if present, of an unusually thin and perishable nature. 
In either case the apparent nakedness of the sides of the body, along with the 
other peculiarities noted, seems amply to justify the erection of the genus 
Phanerosteon. 
Position and Locality —In the Cement-stone group of the Calciferous 
Sandstone series, near Glencartholm, Eskdale. 
Holurus, gen. nov. Traquair. 
Somewhat deeply fusiform; dorsal fin arising behind the middle of the 
back, not acuminate in front, long based, extending almost to the commence- 
ment of the tail pedicle; anal fin with a shorter base than the dorsal ; 
caudal strongly heterocercal, but not bilobate, triangular, its rays gradually 
diminishing posteriorly ; pectorals unknown ; ventrals small, abdominal arising 
slightly in front of the dorsal. Scales rhomboidal, sculptured ; a prominent 
row of median scales between the occiput and the commencement of the 
dorsal fin. Teeth small, cylindro-conical. 
The structure of the head is decidedly paleeoniscoid, with oblique suspen- 
sorium and wide gape, but none of the specimens. afford any evidence of 
* Since the above description was written, a fifth specimen has occurred, with the body as destitute 
of scales as the previous four. 
