24 
ACANIHODII. 
mesial suture. Both these elements have precisely the appearance 
of membrane-bones ; and in some genera (e. g. Parexus, No. P. 130, 
p. 35) the conformation of the scales in the pectoral region so inti¬ 
mately depends upon their form and position, that they are evidently 
of a superficial character. We therefore venture to determine them 
as clavicles and infra clavicles. The truncated extremity of the 
pectoral fin-spine (s.) directly abuts against the angle of the 
supposed clavicle, while that of the mesial spine (m.) is chief!) 
apposed to the same element, though in part also to the infraclavicle. 
The axes of these two spines are inclined towards one anothei, and 
at their proximal extremity they are firmly united by a triangular 
mass of hard tissue (6), which is probably to be regarded as the 
basipterygium or basal cartilage. 
A ? 
BiplacaitfSms striatus, Agassiz. 
1841. “ Ichthyolite,” H. Miller, Old Bed Sandstone, pi. viii. fig. 2. 
1842. Diplocanthus crassisipvus , P. Duff, Geol. Moray, p. 71, pi. x. fig. 2. 
1844. Diplacanthus striatus , L. Agassiz, Poiss. Boss. "V. G. B. pp. 34, 
41, pi. xiv. figs. 1-5. 
1844. Diplacanthus striatulus, L. Agassiz, ibid. pp. 34, 42, pi. xiii. figs. 
//irA /AnV 3,4. [ Forr es Museum and British Museum.] 
Neu. ckodtel 1844. Diplacanthus crassispinus, L. Agassiz, ibid. pp. o4, 43, pi. xiii. 
(b.Jea<nYyit.( ( lz'* 0 figs. 1, 2, pi. xiv. figs. 6, 7. [British Museum, in part.] 
1848. Diplacanthus gibbus , F. M‘Coy, Ann. Mag. Nat. Hist. [2] vol. ii. 
p. 301. [Woodwardian Museum, Cambridge.] 
1855. Diplacanthus gibbus , F. MHoy, Brit. l alseoz. Foss. p. 584, pi. ii b. 
fig. 4. 
1888. Diplacanthus striatus, B. H. Traquair, Geol. Mag. [3] vol. v. 
p. 512. 
Type. Nearly complete fishes; Edinburgh Museum (in part). 
The type species, usually attaining a length or O'07—OH. Body 
robust, but elongated, the greatest depth being contained about 
four and a half times in the total length. Fin-spines very stout, 
coarsely striated longitudinally. Pectoral fin-spines much arched 
and sharply pointed, the median spines relatively large ; pelvic fin- 
spines scarcely half as large as the pectoral. First dorsal spine 
much stouter and larger than the second, placed almost immediately 
above the pectoral arch; second dorsal spine opposed to the anal 
and somewhat larger than the latter. Scales smooth. 
Form. 6)” Log. Lower Old Bed Sandstone : Cromarty, Banffshire, 
Nairnshire, Boss-shire, and Orkney Isles. 
19073-74. Imperfect specimen, in counterpart; Cromarty. • 
Purchased , 1845. 
