162 
PROCEEDINGS OF SOCIETIES. 
from whence it was forwarded, by the kindness of Professor Melville, to the Museum 
of the Royal Dublin Society. It belongs to the sixth order of the second sub¬ 
division of osseous fishes—namely, the Plectognathi, or fishes with soldered jaws. 
In structure, this fish is intermediate between the osseous and cartilaginous fishes, 
the skeleton, approaching the fibrous character of the former, still is slow to 
ossify, especially the costal arches. The palate-bone is firmly united to the 
skull, and, consequently, devoid of motion, in this respect differing from the 
osseous, as also in having the maxillary and intermaxillary bones fused toge¬ 
ther, so as to form one piece, their union being marked by a mere groove. The 
gill rays are completely covered by the opercula, which latter form a perpendicular 
slit of about one inch long. The dental formula is the teeth being set in 
a semi-osseous or muco-cartilaginous nidus, well adapted to the habits of the 
creature, as feeding for the most part on the polypi of coral reefs, the teeth are 
formed for browzing, and, in all probability, grow much after the manner of 
rodents—that is, from behind forwards. 
“ This specimen,indeed I may say the entire genus, though provided with pelvic 
bones, still are destitute of ventral fins. It is true they are furnished with a few 
short spines, in or about the situation of the pelvis, which may be considered as 
the rudiments of these organs. 
“As this fish lives upon food not requiring great complexity for its digestion, we 
accordingly find that its internal organization is not elaborate. The stomach is 
capacious, but the intestinal canal, though of considerable size, is destitute of 
coeca. It is provided with a swim-bladder, to enable it to remain near the surface 
of the water whilst engaged in seeking its food among the coral reefs, where it loves 
to dwell. It possesses two sets of scales, those near the head tubercular or warty— 
hence, scleroderme; secondly, those on the centre of the body, like the scales of 
the osseous fishes, but that in these fishes they do not overlap as in the latter. 
“ It is named “ Pile-fish,” in consequence of the first dorsal spine being covered, 
on its anterior edge, with rough granular projections; and the term “ Balistes” 
has reference to another peculiarity in the structure of that spine and the one im¬ 
mediately adjoining, which peculiarity Salviani was the first to discover—viz., that 
the bones, or rays, of the first dorsal fin are so contrived as to act in concert, with 
considerable force, in suddenly elevating the fin at the pleasure of the animal; 
though the foremost, or largest, be pressed ever so hard, it will not stir; but, if 
the last, or least, ray of all be pressed but very slightly, the other two immediately 
fall down with it, as a cross-bow is let off by pulling down the trigger. Por this 
reason the fish is called, at Rome, ‘ j oesce balestra .’ 
“ For the following measurements he was indebted to his friend, Mr. E. P. 
Wright:—Length of specimen, from snout to extreme end of caudal fin, 
sixteen inches; depth seven one-fourth inches, being something less that one- 
half the length; the first spine of the dorsal was unfortunately broken on 
its capture. The head declines gradually from the first dorsal fin, with slight 
depression over the eyes; width of mouth, from centre of jaws, six-eighths of an inch ; 
number of teeth, sixteen, four on each side of both jaws, bent inwards ; eye small; 
orbit six-eighths of an inch in diameter; from eye to eye, across forehead, one 
five-eighth inches; nostrils, situated close to the eye, between it and the upper 
jaw, consist of two small perforations. The fin ray formula is as follows :—• 
1st, D 3 ; 2nd, D 28; P 14 ; A 26 ; C 14. 
“All the rays are slightly free at apex. There is a space of nearly one inch 
between end of anal and beginning of caudal ray; the longest ray of the latter is 
four inches, and the shortest two. The first ray of the dorsal fin is in a vertical line 
over the branchial orifice; the second dorsal and anal both begin in a vertical line. 
A rough skin, covered with scales, takes the place of the ventral ray. These mea¬ 
surements accord pretty nearly to those given by Yarrell, with the exception of the 
pectoral fin, which in his ray formula has fifteen rays ; but both his figure and 
the coloured engraving in the Naturalists’ Library (plate 21, vol. ii., of the British 
Pishes, by Dr. Hamilton), represent the caudal fin as wedge shaped ; whereas in 
this specimen, as will be seen from the above measurements, it forms the arc of a 
large circle. Its colour is brownish gray.” 
