76 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 
A genus of peristediids known by its greatly developed spines, as 
frontal, supraorbital, occipital, opercular and preopercular pairs, be- 
sides the spiny series on the body and all more or less rugose striate. 
Also all the barbels small and anterior simple. Very conspicuous and 
distinctive are the exceptionally long pair of occipital spines, well- 
inclined back. 
(axkavOa, spine+-ornbiov, from Peristedion.) 
ACANTHOSTEDION RUGOSUM, new species 
Figure 17 
Depth 5 in body as measured from snout tip inside rostral extensions ; 
head 1%, width 114. Snout 214 in head; eye 5, 2 in snout, 1 in 
interorbital; maxillary extends halfway to eye, length 734 in head; 
mouth width 3814; anterior mandibular barbel 7, posterior 224, 
front pair simple; mouth edentulous; interorbital 434, concavely de- 
pressed. Gill rakers 8+20?, finely lanceolate, over twice gill filaments 
or 2 in eye. 
H. W.F. del. 
Ficure 17.—Acanthostedion rugosum, new species: Type (U.S.N.M. No. 99501). 
Pair of long isosceles triangular extensions, flat or depressed, moder- 
ately wide interspace about 34 to 4% of basal width of either exten- 
sion; large postero-supraorbital spine half of eye diameter in length, 
its front edge finely serrated; very long, strong, inclined occipital 
spine 1+1% times eye diameter, extends back to base of last dorsal 
spine; opercular spine moderate or small, without distinct keel for- 
