PISCES. 169 



PTYCH ACANTHUS. L. Agassiz, Poiss. Foss., vol. iii (1837), 

 p. 22. = Tristychius and undetermined genera. 



dubius, L. Agassiz, Poiss. Foss., vol. iii (1843), p. 176, and Poiss. 

 Foss. V. G. R. (1844), p. 1 j 8, pi. xxxiii, f. 22, 23 ; J. Morris, 

 Cat. Brit. Foss., 1854, p. 341. [Undetermined ichthyolite.] 

 LOC. L. Old Red Sandst. ; Abergavenny. [Spine ; olim Mur- 

 chison Coll.] 

 subhevis, Agassiz. v. Tristychius arcuatus. 

 ? sp., L. Agassiz, in Murchison's Silur. Syst. (1839), p. 597, pi. i, 

 f. 9, 10 ; J. Morris, Cat. Brit. Foss., 1854, p. 341. 

 LOC. L. Old Red Sandst. ; Abergavenny and Herefordshire. 

 [Spine ; olim Murchison Coll.] 



TTYCHOCEFHALUS. L. Agassiz, Poiss. Foss., vol. v, pt. ii 



(1843), p. 139 (name only), and Rep. Brit. Assoc, 1844 



(1845), P- 3°7 (name only). 



radiatlis, L. Agassiz, ibid. (1843), p. 139 (name only), and ibid., 



1844, p. 307 (name only). 



LOC. London Clay ; Sheppey. [Imperfect head; Brit. Mus.] T. 



FTVCUOOUS, L. Agassiz, Poiss. Foss., Feuill., p. 54 (1835), and 

 vol. iii (1839), p. 150 ; A. S. Woodward, Cat. Foss. Fishes 

 B. M., pt. i, 1889, p. 132. 

 AULODUS, F. Dixon, Geol. Sussex, 1850, p. 366. 



acutus, L. Agassiz, Poiss. Foss., vol. iii (1843), P- 1 77 (name only) : 

 recorded from Gault of Folkestone by J. Morris, Cat. Brit. 

 Foss., 1854, p. 341. 



altior, Agassiz. v. Ptychodus mammillaris and P. rugosus. 



arcuatus, Agassiz. v. Protosphyraena (fins of). 



artlculatus, Agassiz. 7'. Protosphyrasna (fins of). 



concentrlcus, named variety of P. poly gyrus (L. Agassiz, Poiss. 

 Foss., vol. iii (1839), p. 156). 



decurrens, L. Agassiz, Poiss. Foss., Feuill., p. 54 (1835), an< l 

 vol. iii (1839;, p. 154, pi. xxv b, f. 1, 2, 4, 6-8 (non f. 3, 5) ; R. 

 Owen, Odontogr. (4840), descr. to pis. xviii, xix ; F. Dixon, 

 Geol. Sussex, 1850, p. 362, pi. xxx, f. 7, 8, pi. xxxi, f. r, 

 pi. xxxii, f. 5 ; J. Morris, Cat. Brit. Foss., 1854, p. 341 ; A. S. 

 Woodward, Quart. Journ. Geol. Soc, vol. xliii, 1887, p. 123, 

 pi. x, f. 1-10, 13, and Cat. Foss. Fishes B. M., pt. i, 1889, 

 p. 138. [See also P. Wdmmillaris.] 



' Palate of Unknown Fish,' J. Parkinson, Organic Remains, 

 vol. iii, 181 1, p. 262, pi. xviii, f. 12. 



Ptychodus depressus, F. Dixon, Geol. Sussex, 1850, p. 363, 

 pi. xxxi, f. 9 ; J. Morris, Cat. Brit. Foss., 1854, p. 341. 

 [Tooth ; Brit. Mus.] 



LOC. U. and L. Chalk ; Sussex, Kent, Surrey, Cambridgeshire, 

 and Norfolk. [Teeth ; Brit. Mus. {pars).'] 



depressus, Dixon, v. Ptychodus decurrens. 



