48 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



Body elongate, compressed (not angiilated), rather deep ; width of 

 body at base of pectorals, 2 in head ; head narrow, compressed, almost 

 trenchant below ; inteorbital area flattish, about as wide as eye, 3 in 

 head. 



Snout short, rather pointed; its length 4J in head; teeth on tongue 

 and palatines; gill rakers numerous, long and slender ; pectoral fins of 

 moderate length; their length If to 2 in length of body; their tips 

 reaching middle of base of dorsal fin; second ray of pectorals divided; 

 dorsal fin very high, its longest rays about ^longer than head; base of 

 dorsal about ly in length of head ; tips of anterior rays of dorsal reach- 

 ing beyond tips of posterior rays when the fin is deflexed, and reach- 

 ing almost to base of caudal fin. Ventrals rather short, 4| in length 

 of body, their tips reaching slightly past origin of anal fin. Origin of 

 ventrals midway between pupil and last caudal vertebra. Anal fin op- 

 posite dorsah Lower lobe of caudal rather short, sligbtly longer than 

 head. Color blue above ; silvery below. Pectorals (dusky in the 

 young) becoming nearly white in the adult; color of ventrals very simi- 

 lar to pectorals, the duskiness in the young formed of fine blackish 

 dots. Upper half of anterior rays of dorsal fin black. Anal fin with 

 few small black dots, more numerous in the young; caudal dusky red- 

 dish. 



Genus III.— HALOCYPSELUS. 



Halocypselus, Weinland, Proc. Bost. Soc. Nat. Hist., 1859. 385 (" mesogaster"* 

 . Weinlaiid = ecolans.) 



This genus is distinguished from Exoccetvs chiefly by the small size and 

 anterior position of the ventrals. There are probably but two species, 

 one of them, H. evolans, being the most widely distributed of all the 

 flying fishes ; the other, II. Iiolnbi Steindachner, is known only from the 

 west coast of Africa. This species differs from H. evolans chiefly in the 

 much higher dorsal. 



ANALYSIS OF SPECIES OF HALOCYPSELUS. 



a Origin of ventral fins midway between tip of snout and last ray of anal; length 

 of ventrals half length of head. Pectorals 1 J in length of body, their tijis reach- 

 ing base of caudal; first ray of pectoral simple; second divided. Anal fin loug, 

 scarcely shorter than dorsal, its first ray usually opposite to first ray of dorsal. 

 Dorsal low, its first ray less than half head. Lower lobe of caudal about one- 

 fourth longer than head. Snout rather blunt, 4^ in head; iuterorbital area flat- 

 tish, 3 in head. Eye 3| in head. Head 4 in length ; depth 5J. D. 13 ; A. 13. 

 Scales about 42. Pectoral fins dark above, with the lower margins white ; no 

 white oblique cross-bar. Ventrals white. Caudal dusky. Dorsal and anal pale, 

 without black markings; a white streak along base of anal, wider and more 

 conspicuous anteriorly Evolans, 3. 



* Although Dr. Weinland refers to E. mesogasfer as the type of Halocypselus, it is 

 evident from his description that he had E. erolans in mind. He says: "In E. meso- 

 gaster the ventrals are very short, about one-fourth as long as the pectorals, and 

 placed anterior to the middle of the body, between the anus and the pectorals ; the 

 shape of the lower jaw is also angular." For the mesogaster, thus diagnosed, he pro- 

 poses a new genus, Halocypselus. 



