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PROCEEDINGS OF THE NATIONAL MUSEUM. 



vol. 38. 



tral, especially posteriorly; caudal peduncle moderately broad, 

 6trongly compressed, and rather short, barely tapering, if at all, 

 viewed laterally; head rather short, especially from snout to occiput, 

 compressed, conical, varying in concavity of dorsal outline in sex, 

 and straight from corner of mouth to below pectorals; its longitu- 

 dinal axis tilted decidedly upward to about •'!() degrees from body 

 axis, owing to 1<>\v position of opercular plates; snout strongly gib- 

 bous from above nostrils to tip, mouth oblique; lower jaw equal to 

 upper, included laterally: maxillary extending to below a point mid- 

 way between pupil and posterior margin of eye; eye large, very close 

 to angle of mouth, the suborbital hones very narrow. 



Dentition very complete; vomer toothless, small; parasphenoids 

 extending far forward, with strong canines, a large series on each 

 side, one or two smaller series between, usually two posteriorly, 

 these strongest in the male; palatines with one large series each of 

 canines; ecto- and entopterygoids with hands of villiform teeth; 



■ m 



.• 



\ . 



Fig. 2.— Hiodom tergisus. 



glossohyal toothed similarly to parasphenoid, but with a central 

 hand of villiform teeth, the area broader; premaxillaries with a 

 single -eric- of small teeth, set widely, visible when jaws are closed; 

 maxillaries with a minute series larger anteriorly; dentaries with 

 inner and outer small series, and between a band of minute teeth. 

 Teeth of dentaries closing against those of palatines. 



Lateral line straight, nearer dorsum; scales fairly large, larger than 

 subopercle, thin, with transparent, flexible margin, two series inclos- 

 ing the base of anal fin. Adipose formation over preorbitals and 

 from dorsal edge of e\ e to upper attachment of opercle; vent ral scale 

 present , half of vent ral length. 



Dorsal fin inserted somewhat behind insertion of anal, about over 

 the ninth ray, contrasting with that of IIi<></oii tergisus and II. 

 sehnops, in which the insertion is well in advance of the vent; the 

 fin l'»w. it- hei-lii \ : . in head, it- base -holt, two-thirds its height, 

 htly concave; caudal deeply forked, its lower lobe longer; pec- 

 torals long, reaching six-sevenths of distance to ventrals; latter 



