158 PROCEEDINGS OF THE ACADEMY OF 



scales are much deeper than long, anteriorly truncated and posteriorly rounded 

 off or convex. The color is olivaceous brown, with a dark greyish tint along 

 the back, and a golden tint beneath. 



We propose calling this species Cyprinodon calif orniensis. 



LXII. Another Cyprinodon, the largest species so far observed in North 

 America, was collected by Mr. John Potts, in Chihuahua river. Specimens of 

 the male sex measure two inches and a half in total length. The head, which 

 constitutes somewhat more than the fourth of the total length, is rather large, 

 the snout being abbreviated and rounded off. The eye is of moderate develop- 

 ment, since its diameter enters four times in the length of the side of the head. 

 The mouth is of medium size. The dorsal region between the nape and the 

 origin of the dorsal fin is very convex ; the depth, measured across the latter 

 region, is a good deal more than the third of the total length. The origin of 

 the dorsal fin is nearer the insertion of the caudal fin than the apex of the 

 snout, the fin itself is higher than long, superiorly convex, the first and second 

 rays being the shortest. The posterior margin of the caudal is subtruncated. 

 The anal has the same shape and structure as the dorsal, but is a much smaller 

 fin. The ventrals overlap the vent, reaching almost the anterior margin of the 

 anal. The pectorals are well developed, rounded off, and extend further back 

 than a vertical line drawn at the insertion of the ventrals. The rays are : D 

 12 ; A 12 ; C 5 1, 7, 7, 1, 4 ; V 6 ; P 14. The body of the female sex is not so 

 deep as in the male, although the dorsal region is convex, resembling some- 

 what C. macidarius, figured on plate xxxvii, of the Ichthyology of the United 

 States and Mexican Boundary Survey. The dorsal and anal fin are likewise 

 much smaller than in the male and composed each of eleven rays instead of 

 twelve ; the upper edge of the dorsal being sublinear instead of being convex. 



The ground color is olivaceous yellow with a golden reflect, much brighter 

 beneath than above, where a greyish tint predominates. The adult male is 

 nearly unicolor ; the base of the caudal fin above is speckled with black, 

 whilst its posterior margin is jet black. In its immature condition the male 

 sex exhibits transverse fascise of blackish brown like the female, which is 

 moreover maculated along the flanks. The base of the caudal is likewise 

 speckled in the female, but the posterior edge of its caudal is not margined 

 with black. On the other hand, a black spot may be seen at the posterior por- 

 tion of the dorsal with specks of the same tint along its base. 



We have bestowed the name of Cyprinodon eximius upon the species which 

 is here described. 



LXIII. The sun fish described by S. F. Baird, under the name of Pomotis 

 chcetodon, in the ninth annual report of the Board of Regents of the Smithson- 

 ian Institution, 1855, 324, possessing all the generical features which we have 

 lately assigned to the genus Bryttus in the report upon the fishes collected 

 during the various Pacific Railroad Surveys, that species we shall henceforwards 

 call Bryttus choztodon. 



LXIV. The Atlantic coast of the United States furnished a small herring, which 

 was first indicated by Mitchill under the name of Clupea teres. DeKay, in his 

 Fauna of the State of New York, has placed it in the genus Alosa. We have 

 examined a series of specimens of that fish, collected by S. F. Baird, along the 

 coast of New Jersey. The largest ones measure about four inches and a half 

 in total length ; all of them in the most perfect state of preservation. Find- 

 ing teeth upon the maxillar bones, the tongue, the palatines, and the ptery- 

 goidians, whilst the vomer is toothless, we propose referring that species to 

 the genus Harengula of Prof. Valenciennes, established in the " Histoire 

 Naturelle des poissons " upon the characters just alluded to, and to call it 

 Harengxda teres. 

 LXV. The fresh water siluroid, described by Lesueur under the name of 



[May, 



