184 U. S. p. R. K. EXP. AND SURVEy§ — ZOOLOGY — GENERAL REPORT. 



PHANEKODON FURCATUS, Grd. 

 Plate XXXIV, Figs. 1—5. 



Spec. Char.— General form elongated, rather tapering posteriorly, and very much compressed. Cleft of mouth not e.xlending 

 to the anterior rim of the orbit. Eyes large and circular. Branchiostegals five in number. Caudal slender and deeply forked. 

 About sixty-three scales in lateral line. Yellowish brown above ; lighter on the sides ; whitish under the throat. Fins yellowish. 

 Margin of dorsal and caudal greyish. A difiused marginal spot upon the anterior portion of anal. 



S\s. —Phanerodon furcatus, Grd. in Proc. Acad. Nat. Sc. Philad. VII, 1854, l.')3 ; and, VH, 1855, 322. 



The general form of the body has a rather elongated appearance, posteriorly tapering towards 

 a slender caudal peduncle, which terminates into a slender and deeply forked fin. It is very 

 much compressed. The head, which constitutes about the fifth of the length, is rather small, 

 slightly dciu'essed above the eyes. The snout is abbreviated and rounded ; the mouth small, 

 and the teeth, proportionally large, are disposed upon one single row on either jaw ; about 

 twelve on the upper and fourteen on the lower, occupying most of the circumference of the 

 mouth. The lips are well developetl, but quite thin, and the frenum which unites the lower 

 one to tl.e symphysis of the jaw is exceedingly narrow, and might easily be overlooked. The 

 premaxillaries are very protractile ; the jaws are perfectly even when the 'mouth is closed. 

 The posterior extremity of the maxillaries do not quite reach a vertical line passing immediately 

 in advance of the anterior rim of the orbit. The eye is large, circular, and its diameter com- 

 prised about three times and a half in the length of the side of the head, exactly once in 

 advance of its anterior edge. The anterior nostril is placed about midway between the orbit 

 and the extremity of the snout. The branchiostegal rays are five on either side, the inferior one 

 being exceedingly slender. A vertical line drawn from the origin of the dorsal fin intersects 

 the middle of the base of the pectorals. The spinous portion of that fin is gradually rising 

 from the first to the last spine, which is a little shorter than the first articulated ray, whence 

 the fin again diminishes in height towards the last articulated ray. The soft portion is one- 

 third longer on its base than the spinous ; the articulated rays are slender, and bifurcate but 

 once beyond the middle of their length. The caudal fin, wliich is contained about four times 

 and a half in the total length, is deeply forked, and provided upon the base of its rays with 

 small and irregularly arranged scales. The rays divide three times, the central ones only 

 twice. The anal fin is long and low ; its base is contained four times in the total length, and, 

 consequently, longer than the base of the soft portion of the dorsal, wliich enters in the total 

 length about four times and a half. Its external margin is slightly concave upon its middle. 

 The anterior spines are slender and well developed, the tliird being nearly as long as the last 

 articulated ray. About nine of the anterior articulated rays are undivided ; the others bifurcate 

 once like those in the dorsal fin. The tips of the ventrals extend as far as the first anal spine ; 

 their insertion is under the vertical line of the third dorsal spine. The articulated rays of these 

 fins bifurcate twice. The pectorals are long and slender, extending backwards to a vertical 

 line which would intersect the fourth articulated ray of the dorsal and the second anal spine. 

 Their rays bifurcate twice. 



The formula of the fins is as follows : 



Br. V : V ; D XI, 2-1 ; A III, 9 -»- 23 = 32 ; C 3, 1, 6, 6, 1, 2 ; V I, 5 ; P 18. 



