66 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



caudal fin. In Plate III is given a photographic reproduction of 

 one of the original specimens serving for Newberry's description. 



Semionotus tenuiceps (Agassiz). 



1836. Eurynotus tenuiceps L. Agassiz, Poiss. Foss., ii, pt. 1, 



pp. 159, 203, pi. 14c, figs. 3, 4, 5. 



1837. Palceoniscus latus J. H. Redfield, Ann. Lyceum Nat. 



Hist. N. Y., iv, p. 38, pi. 2. 

 1837. Eurynotus tenuiceps J. H. Redfield, ibid., p. 39. 

 1841. Eurynotus tenuiceps E. Hitchcock, Geol. Mass., ii, 



p. 459, pi. 29, figs. 1, 2. 

 1841. Palceoniscus latus W. C. Redfield, Am. Journ. Sci., 



[1] xli, p. 25. 

 1850. Ischypterus latus Sir P. G. Egerton, Quart. Journ. 



Geol. Soc, vi, p. 10. 

 1857. Eurinotus ceratocephalus E. Emmons, Am. Geol., 



pt. 6, p. 144, pl. 9 a - 

 i860. Eurinotus ceratocephalus E. Emmons, Manual Geol., 



2d ed., p. 188, fig. 164. 

 1877. Ischypterus latus R. H. Traquair, Quart. Journ. Geol. 

 Soc, xxxiii, p. 559. 



1888. Ischypterus tenuiceps J. S. Newberry, Monogr. U. S. 



Geol. Surv., xiv, p. 32, pl. 5, figs. 1-3, pl. 7, fig. 3- 



1889. Allolepidotus americanus W. Deecke, Palaeontogr., 



xxxv, pp. 103, 114. 

 1895. Semionotus tenuiceps A. S. Woodward, Cat. Foss. 



Fishes Brit. Mus., pt. 3, p. 59. 

 1903. Semionotus tenuiceps G. F. Eaton, Am. Journ. Sci., 



[4] xv, p. 295. 

 1905. Semionotus tenuiceps C. R. Eastman, Ann. Rept. 



N. J. Geol. Surv. for 1904, p. 87. 



A species attaining a total length of about 20 cm., and readily 

 distinguished from all others (except in young stages) by the 

 excessive development of the dorsal ridge-scales ; these are very 

 large and conspicuous, and, in mature individuals, comparatively 

 obtuse. The anterior dorsal outline is considerably arched, 

 usually forming a characteristic "hump" immediately behind 

 the head. Length of head and opercular apparatus less than the 



