64 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 84 



of the pectoral base. Body covered with minute scales imbedded in 

 the skin, snout and lower jaw naked; a flat band of diverging scales 

 follows the base of the dorsal and anal fins throughout their length, 

 those of the dorsal region continue forward to the occiput. Scales 

 with 22 radiating striae. Myomeres evident, 22 body and 27 caudal 

 =49 muscular impressions. Vertebrae, 26 body and 27 caudal=53. 

 Color brownish, with many small dark spots about size of pupil, the 

 lighter ground color forming reticulations on the back, some dark 

 shades radiating from the eye and dark bars across lower jaw, dark 

 bars follow the course of the muscular body ridges well down on the 

 flank; belly and fins plain, translucent. 



One specimen of this rare fish from the Pacific side of the Isthmus 

 of Panama. Collected by Prof. Manuel Valerio. Length 59 mm. 

 U.S.N.M. no. 101379. 



This species is most closely related to M. hildebrandi, new species, 

 differmg notably in the position of the vent and in fin-ray and myomeric 

 counts. 



MICRODESMUS AFFINIS Meek and Hildehraixl 



Figure 11, a; Plate 2, Fioxjre 4 



Microdesmus afjinis Meek and Hildebrand, Publ. Field Mus. Nat. Hist., 

 zool. ser., vol. 15, pt. 3, pp. 955-6, pi. 98, fig. 1, 1928 (Chame Point, Panama). 



Body elongate, of nearly equal depth throughout, somewhat com- 

 pressed. Lower jaw strongly projecting with a small fleshy lump at 

 the symphysis. Caudal mthout fin shorter than rest of bodj^; vent 

 midway between occiput and base of caudal fin. Head 10.5 in stand- 

 ard length; depth 16.8; predorsal 7.4; preanal 1.9; caudal 2.1; preven- 

 tral 10.1; base of ventral to vent 2.3; snout 5.4 in head, measured to 

 upper end of gill opening; interorbital 7.7. Dorsal 69, anal 43, 

 pectoral 12, ventrais 1-3. Eye rather small, high, not fully lateral, 

 the upper run leaning a little to the median line, 1.7 in snout; mouth 

 small, little oblique, the gape about reaching anterior border of the eye ; 

 snout and lower jaw with well-defined longitudinal ridges. Lips 

 thin, with small lateral flanges, the lower of which is shghtly the 

 larger; nostrils placed as in related species. Teeth smaU, close-set in 

 two series in the jaws, none on the palatines or vomer. Gill openings 

 restricted laterally, extending from base of middle pectoral rays 

 obUquely downward and forward to below lower ray of fin, length of 

 the opening about equal to width of pectoral base. Dorsal and anal 

 fins long and low, similar, though the latter much shorter, both 

 fins joined to the caudal at base; origin of dorsal above posterior third 

 of the pectoral length. Body covered with minute scales as in 

 related species, snout and lower jaw naked. Scales with 19 radiating 

 striae. Myomeres evident, 30 body and 33 caudal = 63 muscular 

 impressions. Vertebrae, 28 body and 34 caudal =62. Color uniform 

 olivaceous, fins translucent, caudal sUghtly darker. 



