60 PROCEEDINGS OP THE ACADEMY OP 



The throat and inferior surface of the head exhibit the same tint as the abdo- 

 men. The sides of the head are yellowish brown, whilst its upper surface is 

 rather dark and blackish. Finding no species on record with which the pre- 

 sent one can be identified, the name of Fundulus seminolis may not be deemed 

 inappropriate to designate it henceforward. 



IX. The fish which we have formerly described (Proc. Acad. Nat. Sci., 

 Philada. vi. 1853, 389), under the name of Fundulus tenellus, from specimens 

 obtained at Prairie Mer Rouge, La., and Russellville, Ky., belongs to the genus 

 Zygonectes, proposed by Professor Agassiz (Amer. Journ. of Sci. and Arts, 

 second series, xvi. 1853, 135), so that its present systematic name will be Z. 

 tenellus. We should not be surprised at all to hear that the latter is identical 

 with either one or the other of the sundry species of that genus, which Professor 

 Agassiz has named without characterizing (Amer. Journ. of Sci. and Arts, sec- 

 ond series, xvii. 1S54, 353), except by alluding to their coloration. The cha- 

 racters of the genus itself, were never defined, so that ere long, we may expect 

 to encounter as much difficulty in identifying its species, as we meet with those 

 recorded in the " Ichthyologia Ohiensis." 



X. The party under Lieut. J. C. Ives, has brought home a very remarkable 

 species of Hydrargyra, which was collected ' ' between Fort Defiance and Fort 

 Union, New Mexico." It is probable, therefore, that it was caught in one of 

 the upper affluents of the Rio Grande del Norte (Rio Bravo). 



The average size of the specimens now before us is about three inches, in males 

 as well as in females. The sexual differences reside, as usual in this genus, in the 

 dorsal and anal fins, which are more developed in the male than in the female. 

 The body is elongated, compressed, and subfusiform in profile ; the back being 

 slightly arched. The head is subpyramidal, very much depressed above, en- 

 tering about four times and a half in the total length, and apparently some- 

 what smaller in proportion in the female than in the male. The eye is subel- 

 liptical ; its longitudinal diameter being contained four times, or a little more, 

 in the length of the side of the head. The dorsal fin is longer than higb ; its 

 base entering six times and a half in the total length ; its origin, in the male, 

 is nearly equidistant between the apex of the snout and the posterior margin 

 of the caudal, whilst in the female it takes place much more posteriorly. The 

 insertion of the anal fin is the same, with reference to the dorsal in either sex, 

 but, since the posterior portion of the dorsal, in the male, is more developed 

 than in the female, the consequence is that it is nearly even with the posterior 

 extremity of the anal, whilst in the female, the latter stretches considerably be- 

 yond the extremity of the dorsal. The anal fin itself is as long as deep in the 

 male, and deeper than long, in the female ; exteriorly rounded off in either 

 sex. Its anterior margin, in the female, is overlapped by the membranous 

 expansion of the genital foramen. The caudal fin is subtruncated. The ven- 

 trals are short and broad ; their extremities reaching the anterior margin*of the 

 anal in the male, which is not the case in the female. The pectorals are of 

 moderate development, subovate in their outline, approximating by their ex- 

 tremity the insertion of the ventrals in the male, remaining more apart in the 

 female. The numbers of the fins rays are ; D 13 ; A 14; C 6, 1, 7, 7, 1, 6 : 

 V 5 ; P 17. The scales are comparatively smaller than in H. similis, and differ 

 furthermore from those of the latter species in being much deeper than long. 

 They are subquadrangular in shape, and furrowed upon their anterior section 

 alone. The ground color of the upper region of the head and body is olivace- 

 ous-brown, with a blackish, small spot upon either scale, giving that region 

 quite a dark appearance : whilst a yellowish tint prevails along the sides and 

 beneath. Transverse, narrow black bars or bands, much more conspicuous in 

 the male than in the female, may be observed from the insertion of the pecto- 

 rals to the base of the caudal, about sixteen in number, and extending from 

 the dorsal line to the belly. The intervening spaces are somewhat wider than 



[Feb. 



