we 
. 
152 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 
form; anterior margin descending rather abruptly, obtusely rounded; 
basal margin somewhat sinuous posteriorly. Surface deeply sulcated 
for the greater portion, the sulci mainly disappearing on the umbonial 
slope, where they give place to finely crowded striz; apex acute; mus- 
cular impressions impressed; margin minutely crenulated. 
Length, 12 inches. (No. 2490.) 
Aquia Creek, Virginia. 
APRIL 25, 1880. 
DESCRIPTION OF A NEW AGONOID FISH (BRACHYOPSES XVYOSTER- 
NUS), FROM MONTEREY BAY, CALIFRORNEA. 
By DAVID S. JORDAN and CHARLES H. GILBERT. 
Brachyopsis xyosternus sp. nov. 
Form of head and body as in Brachyopsis verrucosus Lockington. 
Body elongate, depressed, broadest at the shoulders, thence tapering 
rapidly to the snout, and gradually and evenly to the tail. Snout broad, 
obtuse, depressed, its sides parallel. Mouth terminal, very oblique, the 
lower jaw much the longer, its tip projecting upward above the upper 
profile of the snout. Mandible very broad, its greatest depth one-third 
its length, maxillary reaching to half way between front of orbit and 
pupil. A long barbel three-fourths the diameter of the orbit at its end. 
Premaxillaries anteriorly above the level of the pupil. Jaws with bands 
of vuliform teeth. Vomer and palatines with slight asperities. Nasal 
spines present. No spines on top of cranium. Interorbital space broad, 
concave, from the elevation of the supraocular ridges. Preorbital with 
two spines. A sharp spine on the suborbital at lower posterior margin 
of eye. Preopercle with four processes, the upper one a sharp spine. 
Opercle striate, without spine. Top of head and the upper parts of the 
body without the small prickles which are found in a B. verrucosus. Oc- 
cipital pit obsolete. 
No isthmus, the gill membrane united across the breast. No slit be 
hind the last gill. 
Body with the usual eight series of long keeled plates. Each keel 
terminating in a strong spine hooked backward, striz radiating in every 
direction from the spine. 
Dorsal series of plates 32, 6 before the spinous dorsal, 6 along its base, 
4 between the two dorsals, 5 along the base of the soft dorsal, and 11 
behind it. The two dorsal series uniting immediately behind the soft 
dorsal, the resultant single series round, with radiating striz, the kee- 
and spine obsolete. The two abdominal series similarly unite close be- 
hind the anal fin. 
The plates in the upper lateral series diminish in size forward, becom- 
ing very small anteriorly. The lower lateral series becomes broader for- 
wards as the other series decreases. It terminates abruptly opposite 
