1856.] ' * 181 



without a short and thick ray anteriorly. The anal is shaped like the dorsal. 

 The caudal is furcated. The scales are very large; the lateral line, submedian 

 is slightly deflexed upon the abdomen. 



The large scales will serve to distinguish, upon a first glimpse, this genus 

 from both Hyborhynchus and PimepJiales. 



1. Algoma amara. Ten rows of scales upon the line of greatest depth, five 

 above the lateral line and four beneath it. The upper surface of the head and 

 nape is flattened as in Hydrargyra and Fundulus. Dorsal region pale red ; sides 

 silvery; abdomen whitish. 



Caught in a Laguna near Fort Brown, on the Rio Grand del Norte (Rio Bravo), 

 by John H. Clark, under W. H. Emory. 



2. Algoma pluviatilis. This species has the general aspect of a young Cam- 

 postoma and might easily be taken as such. Its mouth and eye are smaller than 

 in the preceding species. The upper lobe of the caudal is longer than the 

 lower lobe. There are also ten longitudinal rows of scales upon the line of 

 greatest depth. The upper surface of the head exhibits numerous small spines 

 as fishes sometimes have during the breeding season. Color reddish brown 

 above ; yellowish brown beneath. 



Collected near Monterey, New Leon, by Lt. D. N. Couch, U. S. A. 



And sill more curious and remarkable, is the genus 



COCHLOGNATHCS, B. & G. 



^I 



which, under the external aspect of Pimephales presents that unique peculiarity 

 in the cyprinoid family, of having spoon-shaped bony expansions of the jaws. 

 There is one on each side on the upper as well as on the lower jaw exactly as in 

 the genus Tetraodon ; their edge being sharp and cutting. The dorsal fin has the 

 structure of that of Pimephales ; the insertion of the ventrals is situated under 

 the anterior margin of the dorsal, the caudal being furcated. The scales are 

 large, and the lateral line follows the middle of the flanks. The isthmus is 

 rather Avide. The pharyngeals have the same shape and form as in Pimephales ; 

 the teeth, however, are more slender and concave upon the grinding surface, 

 giving them the appearance of being bent backwards. They are of the same 

 type, a little more conspicuously hooked, and disposed upon a single row of 

 four : 4 4. 



CocHLOGNATHUS OKNATUS, B. & G. Proc. Acad. Nat. Sc. Philada. vii. 1854, 

 150. 

 From Brownsville Texas ; collected by Capt. Van Vliet, U. S. A. 



Now, then, the genus 



Hybognathus, Agass. 



General form elongated, rather slender and compressed. The head is sub- 

 conical, the snout overlapj^ing the lower jaw, which is thin and flat, provided 

 upon its symphysis with a small tubercle. The mouth being small, subterminal, 

 and directed horizontally forwards ; there are no barbels upon its angles, which 

 do not reach the anterior rim of the orbit. The eyes are well developed. There 

 is a narrow isthmus. Anterior ray of dorsal longest. Insertion of ventrals 

 situated posterior to the anterior margin of the dorsal. Caudal furcated. The 

 scales are large, higher than long, and the lateral line following the middle of 

 the flanks. Pharyngeal bones very much bent, with a dilatation upon the con- 

 vexity, whilst the upper branch is bent inwards, so as to simulate a curve con- 

 cave from above. The teeth are of the cultriform kind, of the grinding 

 type, very compressed and slightly hooked, and provided with a very narrow 

 grinding surface ; they are disjjosed upon a single row of four : 4 4. 



Amongst the species of this genus which we have before us, none answers spe- 

 cifically to the description of JLnuchalis. We find every where the symphysis of 



