DIPLACAXTHIDiE. 
33 
Type. Fragment of spine. 
An undefined species known only by fragments of fin-spines 
more closely resembling those of Climatius than of any other genus. 
The longitudinal ridges upon the spine are notched, the intervals 
being very short immediately above the base, and at least twice as 
long as these throughout the more distal portion. 
Form. Sf Loc. Lower Old Red Sandstone (Passage Beds) : Here¬ 
fordshire and Worcestershire. 
P. 5092. Two imperfect spines; Tin Mill, Downton, near Ludlow. 
Presented by J. E. Lee, Esq., 1885. 
Climatius (?) latispinosus (Whiteaves). 
1881. Ctenacanthus latispinosus, J. F. Whiteaves, Canadian Naturalist, 
n. s. vol. s. p. 99. 
1889. Ctenacanthus latispinosus , J. F. Whiteaves, Trans. Roy. Soc. 
Canada, vol. vi. sect. iv. p. 95, pi. x. fig. 3. 
1889. Climatius latispinosus , A. S. Woodward, Ann. Mag. Nat. Hist. 
[6] vol. iv. p. 183. 
Type. Detached fin-spines; Geological Survey of Canada, Ottawa. 
An undefined species known only by detached fin-spines, which 
attain a relatively large size. The spines are broad, nearly 
straight, with finely tuberculated ridges and prominent posterior 
denticles. 
Form. $ Loc. Lower Devonian : Campbellton, New Brunswick. 
P. 6223. Imperfect spine. Presented by the Director of the Geological 
Survey of Canada, 1890. 
A doubtful spine is also described as follows :— 
Climatius aculeatus, E.von Eichwald, Leth. Rossica, vol. i. (1860), 
p. 1602, pi. lvii. fig. 20.—Old Red Sandstone; Slawjanka, 
near Pawlowsk, St. Petersburg. [University of St. Peters¬ 
burg.] 
Genus PARES2CUS, Agassiz. 
[Poiss. Foss. Y. G. R. 1845, p. 120.] 
Body deeply fusiform, laterally compressed; caudal fin large and 
powerful. Teeth minute or absent. Fin-spines robust, marked with 
coarse longitudinal ridges; first dorsal spine enormousl} T developed, 
with large posterior denticles ; several pairs of free spines on the 
ventral aspect between the paired fins. 
The first dorsal fin-spine only was knowm to Agassiz, and the 
genus thus remained imperfectly defined until 1864, when Powrie 
discovered a complete example of the type species. 
PART II. 
D 
