GILBERT AND ST ARKS — FISHES OF PANAMA BAY 121 



225. Sagenichthys mordax sp. nov. 



Plate XVI, Fio. 32. 



This species, which comes rather abundantly to the market at Panama, has 

 been identified heretofore with Sagenichthys ancylodon from the Atlantic. No satis- 

 factory material from opposite sides of the Isthmus has ever been compared, and 

 none from the Atlantic is now available to the authors. But if current descriptions 

 of S. ancylodon are at all reliable, there can be no question as to the validity of the 

 form here described, which is distinguished by the greatly enlarged scales along the 

 course of the lateral line, and by the much smaller size of the scales covering the 

 body generally, as shown by the number of oblique rows above the lateral line. The 

 gill-rakers are shorter than in S. ancylodon. 



Dorsal X, I, 28-30; anal II, 9 or 10. Head 3^ in length; depth 4^. Snout ^\ to 4J in 

 head; eyes (between edges of adipose eyelids) 6| in head in adults 38 cm. long, 5^ to 5| in speci- 

 mens 25 cm. long. The width of the bony interorbital space is slightly greater than the distance from 

 the tip of the snout to the posterior nostril, slightly less than 5 times in the head. In younger speci- 

 mens, it equals the length of snout as far as posterior nostril. 



The maxillary is longer in young specimens, its length contained 2 to 2\ times in the head; in 

 larger specimens 2 1 to 2?. The premaxillaries have an outer series of arrow-shaped teeth, which are 

 very long toward the center of tlie jaw, and decrease in size regularly tovvard the angle of the mouth. 

 Anteriorly, behind the outer row, is a short series of three teeth on each side the median line, one of the 

 anterior pair, or rarely both, greatly elongate, much exceeding any of the other teeth in size. 

 Along the posterior half of each premaxillary, there is a narrow inner band of small cardiform teeth, 

 which retain the form of the canines, each tooth having a distinctly lancet-shaped head, and a longi- 

 tudinally-ridged stalk. Near the hinder end of the band, the outer row of canines become so reduced 

 as to be indistinguishable from the teeth lying behind them. The sides of the mandible contain an inner 

 series of large arrow-shaped canines, and a single outer series of slender teeth, similarly provided with 

 arrow-shaped tips. Anteriorly on each side, the inner series of canines terminates, and an outer series 

 of still larger canines develops, consisting normally of four teeth on each side the symphysis, of which 

 the second pair are the largest. These are not continuous with the outer series of small teeth which 

 occupy the sides of the jaw, as the latter bend around behind the anterior canines, where the two 

 series overlap. The larger canines are subject to frequent injury, and are rapidly replaced by others 

 occupying the same position. The lower jaw projects so that the anterior mandibular canines close 

 •outside the upper lip. 



The gill-rakers are proportionately longer in young specimens, in which the longest is one- 

 third to two-fifths the diameter of the eye. There are 7 to 9 movable rakers on the horizontal limb of 

 the outer arch. 



The dorsal spines are very slender and weak. The membrane behind the tenth spine joins the 

 base of the eleventh, which is attached for its entire length to the first soft ray. All the fins are densely 

 scaled to their tips. The caudal fin is doubly concave, the median rays greatly protruding in the 

 young, less so in adults. The pectoral fins are very long, extending nearly twice as far as the ven- 

 trals, i^ to I i in the head in specimens 12 inches long (injured in larger specimens). Ventrals 2 J 

 in head. 



The scales are very small, those above the lateral line arranged in about 105 oblique series 

 running downward and backward. The scales bearing the pores of the lateral line are much enlarged, 

 47 to 50 in number, counted to the base of the median caudal rays. These enlarged scales are covered 

 and in part concealed by small scales similar to those above the lateral line. 



