22 
ACAXTHOMI. 
46305, 46305 a. Four specimens, two being destitute of the tail; 
also an imperfect left mandibular ramus with portions of 
the dentition. Purchased , 1875. 
P. 132-6, P. 141-2, P. 144-8. Twelve specimens, the first preserved 
in counterpart and shown, of the natural size, in PI. I. 
fig. 8. This specimen appears to exhibit the precise out¬ 
line of the fish, without distortion, and all the fin-spines 
are preserved in their natural positions. Two large teeth 
remain in the upper jaw, but the bones and cartilages of 
the head are obscure. A series of short, vertically elon¬ 
gated impressions in the anterior portion of the trunk 
have the appearance of neural arches; though, if so, the 
head has been somewhat displaced by crushing, for a few 
of these impressions occur far forwards. The character¬ 
istic form of the basal cartilage of one pectoral fin is indis¬ 
tinctly shown. Portions of the membrane of the pelvic 
and anal fins are exhibited, and the caudal is apparently 
complete. Purchased , 1880. 
P. 1344. Two small specimens, and one measuring not less than 
0T5 in length. Egerton Coll. 
The following specimen is not certainly determinable, but appears 
to pertain to a large individual of this species :— 
P. 131. Caudal region and hinder portion of the abdominal region 
of an Acanthodian fish, the specimen preserved in counter¬ 
part and measuring 0T3 in length; Lower Old Fed Sand¬ 
stone, Turin Hill, near Forfar. Femains of the pectoral 
spines show that these were of moderate size, slender, 
arched, and finely ribbed. One dorsal spine (presumably 
the second) is situated slightly behind the anal, and the 
caudal fin is very robust. The scales are minute, smooth, 
and faintly hollowed. Purchased , 1880. 
Family DIPL AC ANT HID Hi. 
Two dorsal fins present, both these and the anal with an anterior 
spine. Pectoral arch with clavicular bones. 
Synopsis of Genera. 
A. Paired spines between pectoral and pelvic 
fins insignificant or absent. 
Teeth minute or absent; median pair of 
spines between pectorals . Eiplacanthus (p. 23). 
