﻿rhizodontid^:. 363 



P. 5482-84. Three typical small specimens, the third showing 

 portions of the vertebrae in the abdominal region. 



Purchased, 1888. 



P. 5976-78. Portions of large individuals. Purchased, 1889. 



The two following genera are proved by their dentition to pertain 

 to the Rhizodontidae, but are as yet too imperfectly known for 

 precise definition. 



Genus CRICODUS, Agassiz. 



[Poiss. Foss. vol. ii. pt. ii. 1844, p. 156, pi. H. figs. 9-12.] 



Syn. Polyplocodus, C. H. Pander, Saurodipt., Dendrodont. &c. devon. 

 Syst. 1860, p. 28. 



Bones of fronto-ethmoidal shield fused into a single piece. Teeth 

 rounded in section, with a large pulp-cavity. [Exposed portion 

 of scales probably tuberculated.] 



Cricodus incurvus (Duff). 



1842. Bendrodus incurvus, P. Duff, Geol. Moray, p. 68, pi. vi. fig. 11. 

 1844. Cricodus incurvus, L. Agassiz, Poiss. Foss. vol. ii. pt. ii. p. 162 



(name only). 

 1844. Cricodus incurvus, L. Agassiz, Poiss. Foss. V. G. R. pp. 61, 88, 



pi. xxviii. figs. 4, 5. 



Type. Tooth ; (?) collection of James Powrie, Esq., Reswallie. 



The type species, founded upon a small, stout, recurved tooth 

 about 0-013 in length. 



Form. $ Log. Upper Old Red Sandstone: Scat Craig, Elgin. 

 Upper Devonian : Riga. 



Not represented in the Collection. 



Cricodus wenjukowi, Rohon. 



1860. Polyplocodus incurvus, C. H. Pander {errore), Saurodipt., Dendro- 

 dont. &c. devon. Syst. pp. 82, 84, 86, pi. x. fig. 23, pis. f, g, pi. l. 

 figs. 1-5. 



1880. Bendrodus biporcatus, H. Trautschold {errore), Verhandl. russ.- 

 kais. mineral. Ges. [2] vol. xv. p. 139, pis. iii.-v. 



1889. Cricodus {Polyplocodus) zvenjukoivi, J. V. Rohon, Mem. Acad. 

 Imp. Sci. St.-Petersbourg, [7] vol. xxxvi. no. 14, p. 49, pi. i. figs. 3, 

 4, 6, 11, pi. ii. figs. 12, 14, 19. 



(?) 1889. Bendrodus biporcatus, J. V. Rohon {errore), ibid. p. 49, pi. i. 

 figs. 1, 9. 



1890. Cricodus, H. Trautschold, Zeitschr. deutsch. geol. Ges. vol. xli. 

 p. 629, pis. xxiii.-xxv. 



