NO. 2177. FOSSTL FISHES IN NATIONAL lIUSEUil— EASTMAN. 291 



V. 1-6; vertebrae, 10-18. Scales in twelve longitudinal rows between dorsal and 

 ventral fins, and equal in number to the vertebrae on the longitudinal line, or 28. 

 Head covered with scales; five in a vertical line on the operculum. The dorsal, pec- 

 toral, and ventral fins are rather small. The caudal fin is probably not much forked, 

 if at all. The orbit is large, but its outlines are not well preserved. The head enters 

 the total length four and a quarters times to the base of the caudal fin-rays, and slightly 

 exceeds the depth at the ventral fins. Total length, 61 mm. ; length of head, 15 mm. ; 

 length to base of ventral fin, 24.5 mm. ; length to base of anal fin, 30 mm. ; depth at 

 ventrals, 14 mm.; depth at caudal peduncle, 6 mm. 



Formation and locality. — Oligocene ( ?) Ree Hills, South Dakota. 

 PARAFUNDULUS, new genus. 



A genus closely related to existing killifislies, and also to the ex- 

 tinct Gepliyrura, but distinguished from the latter cliiefly by its 

 smaller and less conspicuously marked scales, 1^'ger number of dorsal 

 fin rays, and presence of a hypural bone. Caudal fin gethyrocercal. 



Type of the genus. — Parafundulus nevadensis, new species. 



PARAFUNDULUS NEVADENSIS, new species. 



Plate 16, fig. 2; plate 17; plate 18, fig. 3. 



A small form attaining a total length of about 5.5 cm., in which 

 the length of the head and opercular apparatus is contained three 

 and one-half times. Dorsal comprising 11 rays, supported by an 

 equal number of interspinous bones, and inserted opposite a point 

 midway between the pelvics and anal. Scales small and thin, with 

 fine concentric markings, crossed by a few inconspicuous radiating 

 proximal striae. 



Fin formula: D. 11; C. 23; R. 10; V. 9; P. 11-12. 



The specimen (Cat. No. 8120) selected as type of this species is 

 photographed of the natural size in plate 16, figm-e 2, and a drawing 

 of it is reproduced in plate 18, figure 3. It is the most perfect of 

 several that were obtained in 1905 by Mi\ N. H. Darton, m strata of 

 very white clay near Hazen, Nevada, which have received the name 

 of Lahonton beds. From the same locality a single species of stickle- 

 back, known as Gasterosteus doryssus Jordan, was described almost 

 simultaneously in 1907 by Drs. D. S. Jordan ^ and O. P. Hay.^ Be- 

 sides the type several other examples of this species, shown in plate 

 17, were collected by Mr. Darton at the same locahty, and are now 

 preserved in the collection of the United States National Museum. 

 The writer is indebted to his colleague, Mr. John Treadwell Nichols, 

 of the American Museum of Natural History, for helpful suggestions 

 in regard to comparing this form and its scale characters with the 

 existing Fundulus. 



Formation and locality. — Lahontan beds; near Hazen, Nevada. 



1 Pub. Univ. Cal., vol. 5, 1907, No. 5, p. 131, figs. 25, 26; Smitlis. Misc. Coll., vol. 52, 1910, p. 117. 

 » Proc. U. S. Nat. Mus., voj. 32, 1907, pp. 271-273, figs. 1-3. 



