44 FOSSIL FISHES OF THE ENGLISH CHALK. 



with ridges and tubercles of ganoine. Premaxilla in the form of a vertical lamina, 

 which is either toothless or with a series of minute teeth ; maxilla long and styli- 

 form, similarly either toothless or with minute teeth where it enters the oral 

 margin ; ectopterygoid bearing a single spaced series of acute, laterally compressed 

 teeth, which are largest in front and sometimes exhibit a single posterior barb 

 towards their apex ; palatine with a double longitudinal series of teeth, the largest 

 behind ; dentary thin, but so bent that it has a wide horizontal extent, with a close 

 series of minute teeth on its extreme outer margin, another close series of larger 

 teeth within this, and a third inner series of relatively large recurved teeth, well 

 spaced, sometimes barbed at. the apex. Operculum strengthened on the inner side 

 by a ridge extending horizontally backwards from the point of suspension. Verte- 

 brge from 50 to 60 in number, about half being caudal ; the centra at least as long 

 as deep, much constricted, and marked with fine irregular longitudinal ridges. A 

 series of large dermal scutes along the dorsal ridge between the occiput and the 

 dorsal fin ; smaller scutes along the course of the lateral line. 



Type Species. — GimoJiclitlnjs leiresiensis, fi'om the English Chalk. 



Bemarhs. — The barbed teeth of this genus (PI. XII, figs. 3, 4) were originally 

 referred by Agassiz, in error, to the Cretaceous Saurodon leanus, Hays, which is 

 quite a distinct fish found in the Greensand of New Jersey, U.S.A. They have subse- 

 quently received other names, and have even been compared with the barbed teeth 

 of the Scombroid Aiienchehvi or Lepidopus. The arrangement of the scutes on the 

 trunk is not completely determined ; but an American fossil provisionally ascribed 

 to the so-called Empo, exhibits three longitudinal series of rhombic scutes on the 

 flank of the abdominal region. Their " apices are directed forwards, and the sur- 

 face has a reticulate sculpture. In another species they appear to be smooth " 

 [Cope). It is thus very probable that the trunk named Plinthopltorus really belongs 

 to CimoUchthys Jeiuesieiisis. 



1. Cimolichthys lewesiensis, Leidy. Plate IX, figs. 10 — 14; Plate XII; Text- 

 figure 10. 



1835-44. Saurodon leanus, L. Agassiz, Poiss. Toss., Feuill. p. 55, and vol. v, pt. i, p. 102, pi. xxv c, 



figs. 30, 31 (errore). 

 1850. Saurodon leanus, F. Dixon, Geol. Sussex, p. 373, pi. xxx, figs. 28, 29; pi. xxxii*, fig. 10 (errore). 

 1857. Cimolichthys levesieneis, J. Leidy, Trans. Amer. Phil. Soc, vol. xi, p. 95. 

 (?) 1864. Plinthoj)horus rohustus, A. Giinther, Geol. Mag., vol. i, p. 115, pi. vi. 

 1878. Cimolichthys levesiensis, E. T. Newton, Quart. Journ. Geol. Soc, vol. xxxiv, p. 795. 

 1888. Cimolichthys levesiensis, A. S. Woodward, Proc. Geol. Assoc, vol. x, p. 316. 

 1901. Cimolichthys lewesiensis, A. S. Woodward, Catal. Foss. Fishes B. M., pt. iv, p. 221. 



Tyjye. — Imperfect ectopterygoid with teeth, from one of the Turonian zones ; 

 British Museum. 



