74 CALIFORNIA ACADEMY OF SCIENCES. 



Gill-membranes forming a much narrower fold across 

 the isthmus than in platypogon. 



Vertical series of pores on the sides of the body. 



Distance of dorsal fin from tip of snout little more 

 than 2i in the length, the spine 1| in the head, its an- 

 terior margin with low, blunt granules. 



Distance [of the adipose from the dorsal fin 4 in the 

 length, adipose fin as long as the dorsal fin minus the 

 fulcrum. Caudal widely forked, 3| in the length. 



Anal little longer than high, deeply emarginate. 



Ventral 2 in the head. 



Metallic blue above, shading into silvery below; inner 

 surface of the pectorals wholly blue-black, except the 

 posterior margin which is light; ventrals lighter, but 

 marked in the same way. 



Head 3f ; depth 5^; D. I, 7; A. 17. 



44. Tachisurus osculus. 



Arius osculus Jordau & Gilbert, Biill. U. S. Fish Comm. 1882, 46 



(Panama). 

 Galekhthys osculus Jordan, Proc. U. S. Nat. Miis. 1885, 366 (name 



only). 

 Tachisurus osculus Eigeum. & Eigenm. Proc. Cal. Acad. 2d Ser. vol. 



i, 1888, 142 (Panama). 

 Habitat: Panama. 



Rather slender, the greatest width equals the depth. 

 Head short and broad, the greatest width 1| in its 

 length; its greatest depth If in its length; interorbital 

 area flattish, smooth; top of head, dorsal plate and 

 humeral process coarsely granular; opercles faintly 

 striate. Occipital process little broader than long, ridged 

 rather than keeled, the margins concave; middle of fon- 

 tanel over the posterior margin of the eye; fontanel 

 produced backward in a groove which is about as long 

 as the eye. 



Eye 2 in snout, 6 in head, 2| in the interocular. 



Maxillary barbels not reaching beyond the gill-open- 



