ICHTH Y ODOTITTLTTES. 
123 
III. Paired spines of which some may have been placed in front of 
fins, but of which many are broad, with insignificant base of 
insertion, and must have been arranged as independent dermal 
armour. 
Genus MACHiERACANTHUS, Newberry. 
[Bull. National Institute, 1857, p. 6.] 
Syn. Mcichcerius, M, Rouault, Oomptes Rendus, vol. xlvii. 1858, p. 102 
(preoccupied). 
Spines, so far as known, elongated, tapering, more or less curved, 
and somewhat laterally compressed, with sharp edges and a large 
longitudinal ridge on each side; central cavity extending nearly to 
*"the apex; external surface covered with a thin layer of gano- 
dentine, smooth, finely punctate, or longitudinally striated. 
Machaeracantlms sulcatus, Newberry. 
1843. u Ickthyodorulite,” J. Hall, Nat. Hist. New York, pt. iv. p. 174, 
woodc. fig. 69. 
1857. Machceracanthus sulcatus, J. S. Newberry, Bull. Nat. Inst. p. 6. 
1870. Machairacanthus sulcatus, E. R. Lankester, Geol. Mag. vol. vii. 
p. 398, woodc. fig. 3. 
1873. Machcer acanthus sulcatus, J. S. Newberry, Rep. Geol. Surv. Ohio, 
vol. i. pt. ii. p. 305. 
1886, Machcer acanthus sulcatus, T. H. Lennox, Proc. Canad. Inst, 
vol. iii. p. 120. 
1889. Machcer acanthus sulcatus, J. S. Newberry, Pakeoz. Fishes N. 
America (Mon. U.S. Geol. Surv. no. xvi.), p. 40, pi. xxix. fig. 5. 
Type. Delaware University, Ohio. 
Porm. Sf Loc. Lower Devonian (Corniferous Limestone) : Ohio, 
New York, Ontario, and Canada. 
P. 6216. Impression of part of spine, apparently the specimen 
figured by Lankester, loc. cit.; Gaspe, Canada, 
Presented by Sir J. William Dawson , K.C.M.G., 1890. 
The following species are also recognized, but there are no 
examples in the Collection : — 
Machcer acanthus cibnormis : Ctenacanthus abnormis, C. G. Giebel, 
Abh. Naturw. Yereins Provinz Sachsen u. Thiiringen, vol. i. 
(1858), p. 264, pi. i. fig. 12 ; J. Barrande, Syst. Silur. 
Boheme, Suppl. to vol. i. (1872), p. 628; E. Kayser, Abh. 
geol. Specialk. Preuss. u. Thiiring. Staaten, vol. ii. pt. iv. 
