﻿354 CROSSOPTERYGII. 



Form, cj- Log. Lower Carboniferous : Horton Bluff, Nova Scotia. 

 Not represented in the Collection. 



An undetermined small species, with teeth resembling those of 

 S. sauroides (Traquair, Trans. Roy. Soc. Edinb. vol. xxx. p. 1 8) is 

 indicated by the following specimens : — 



P. 4054. Two teeth, 0*01 in length, incurved at the apex ; Calci- 

 ferous Sandstones (Cement-stone Group), Eskdale, Dum- 

 friesshire. Purchased, 188,3. 



P. 4054 a. Oval scale, 0'038 in long diameter ; Eskdale. 



Purchased, 1883. 



Scales, with associated teeth, from the Caleiferous Sandstones of 

 Pitcorthy, Pife, are also named Strepsodus minor, R. H. Traquair, 

 Proc. Roy. Soc. Edinb. vol. xvii. (1890), p. 393. [Edinburgh 

 Museum.] 



Other scales much resembling those of Strepsodus have been 

 described from the Upper Devonian of Mimers Dal, Spitzbergen, by 

 E. R. Lankester, Handl. k. Svenska Yetensk. Akad. vol. xx. no. 9 

 (1884), p. 5, figs. 7-12. [State Museum, Stockholm.] Compare also 

 Sauripterus (p. 364). 



A fragmentary scale from the Chatham Series of North Carolina, 

 figured under the name of Rabdiolepis speciosus by E. Emmons 

 (Manual Geol. ed. 2, 1860, p. 183, fig. 161), also exhibits some 

 resemblance to Strepsodus. 



Genus RHIZODOPSIS, Young. 

 [Quart. Journ. Geol. Soc. vol. xxii. 1866, p. 596 l .] 



Syn. Dittodus, R. Owen, Trans. Odontol. Soc. vol. v. 1867, p. 325 (in 

 part). 

 Ganolodus, R. Owen, ibid. p. 354 (in part). 

 Characodus, R. Owen, ibid. p. 366. 

 Gastrodus, R. Owen, ibid. p. 370. 

 Orthognathus, T. P. Barkas, Coal-Meas. Palaeont. 1873, p. 38. 



Body much depressed anteriorly, with narrow ovoid scales, of 

 which the exposed portion is covered with a thin film of ganoine, 

 while the inner face is marked by a median boss and punctations 

 posteriorly. Teeth round in section, smooth. Vertebras ring-shaped. 

 First dorsal fin opposed to the pelvic pair, and the second dorsal to 

 the anal ; tail heterocercal, the caudal fin rhomboidal in form. 



1 This definition is said to be based upon the unpublished observations of 

 Huxley. The generic name is incidentally mentioned by Huxley, Mem. Geol. 

 Surv. dec. xii. (1866), p. 31, footnote. 



