ISCHXACAXTTTTDJE. 
21 
This genus was withdrawn by J. Powrie in 1870 1 , the type 
species being assigned to Diplcicanthus ; but it has lately been once 
more adopted by R. H. Traquair 2 . 
Ischnacanthus gracilis (Egerton). 
[Plate I. fig. 8.] 
1859. Ictinocephalus granulatus , D. Page, Rep. Brit. Assoc. 1858, Trans. 
Sect. p. 105 (name only). 
1861. Diplcicanthus gracilis, Sir P. Egerton, Figs. & Descrips. Brit. 
Organic Remains (Mem. Geol. Surv.), dec. x. p. 69, pi. ix. 
1864. Ischnacanthus gracilis, J. Powrie, Quart. Journ. Geol. Soc. yoI. 
xx. p. 419. 
1870. Diplacanthus gracilis , J. Powrie, Trans. Edinb. Geol. Soc. vol. i. 
p. 290, pi. x. fig. 2. 
1888. Ischnacanthus gracilis, R. H. Traquair, Geol. Mag. [3] yoI. y. 
p. 512. 
Type. Nearly complete fish. \ J 
The type species, attaining a maximum length of about 0 # 12-0*16. 
Body slender and elongated, the greatest depth being contained 
about five times in the total length. Fin-spines slender, coarsely 
striated longitudinally. Pectoral fin-spines gently arched ; no pair 
of free spines between these and the pelvic fins ; pelvic fin-spines 
about two thirds as large as the pectoral, and placed midway 
between these and the anal. Dorsal spines nearly equal in size, or 
the second slightly the larger; first dorsal spine placed well behind 
the pectorals, second dorsal immediately behind the anal, which is 
somewhat smaller. Scales smooth. Large dental crowns robust and 
smooth. 
Form, df Log. Lower Old Red Sandstone : Forfarshire. 
All the following specimens were obtained from Turin Hill, near 
Forfar:— 
38517. Small example. Purchased , 1864. 
38598-99. Nearly complete fish, displaying dentition; and an im¬ 
perfect large specimen, probably exceeding 0*16 in length. 
Presented by James Powrie, Fsq., 1864 . 
41363-64. Trunk with complete tail, and an imperfect crushed 
specimen. Purchased, 1869. 
46303. Imperfect trunk and tail, in counterpart, of an individual 
probably 0*16 in total length. Purchased, 1875. 
1 Trans, Edinb. Geol. Soc. vol. i. (1870) p. 2S9. 
2 Geol. Mag. [3] vol. v. (1888) p. 512. 
