20 
ACANTHODII. 
Oheiracanthus grandispinus, M 4 Coy. 
848. Chiracanthus grandispinus, F. M 4 Coy, Ann. Mag. Nat. Hist. [2] 
vol. ii. p. 300. 
1855. Clnracantlius grandispinus , F. M 4 Coy, Brit. Paleeoz. Foss. p. 582, 
pi. iiB. fig. 1. 
1888. Oheiracanthus grandispinus , R. H. Traquair, Geol. Mag. [3] 
vol. v. p. 512. 
Type. Imperfect fish ; Woodwardian Museum, Cambridge. 
An imperfectly known species, attaining a length of about 0*25- 
0*3. Body comparatively deep and robust. Fin-spines extremely 
stout and longitudinally ribbed, the length of the pectorals not 
equalling the depth of the trunk at their point of insertion. Pelvic 
fins arising midway between the pectorals and the anal, and the 
dorsal midway between the pelvics and the anal. Scales relatively 
small. 
Form. Sf Log. Lower Old Red Sandstone : Orkney Isles, Scotland. 
39186. Middle portion of trunk, with pelvic, dorsal, and anal spines. 
Bowerbank Coll. 
41130. Imperfect head and trunk, wanting the extremity of the 
caudal region. Bryson Coll. 
P. 178-9. Two imperfectly preserved specimens, the first showing 
remains of the head and anterior portion of the abdominal 
region, the second only wanting the extremity of the tail. 
Purchased , 1881. 
Family XSCHNACANTHIDfE. 
Two dorsal fins present, both these and the anal with an anterior 
spine. Clavicular bones absent. 
This family is represented only by the type genus. 
Genus ISCHNACANTHUS, Powrie. 
[Quart. Journ. Geol. Soc. vol. xx. 1864, p. 419.] 
Syn. Ictinocephalus, D. Page, Rep. Brit. Assoc. 1858, Trans. Sect, 
p. 104 (undefined). 
Body fusiform, laterally compressed. Dentition prominent, con¬ 
sisting of few large conical teeth, the interspaces between these 
teeth being occupied by a close series of minute cusps, all apparently 
in firm connection with a membrane-bone in both jaws. Ho median 
pair of spines attached to the pectoral arch between the pectoral 
fin-spines. 
