488 CALIFORNIA ACADEMY OF SCIENCES. 116 
bar from nape to eye; snout dusky; breast and opercles 
silvery. 
This species is the type of the genus Xesurus Jordan & 
Evermann (MS.), distinguished from Przonurus by the 
armature of the caudal peduncle, as above described. 
Family BALISTIDA. 
188. Balistes polylepis Steindachner. PEz PuERco. 
Generally common in rocky places on the coast from 
Magdalena Bay to Panama. Many specimens were ob- 
tained by us, the largest of them sixteen inches in length. 
It was found at Mazatlan also by Gilbert and by Steind- 
achner. 
189. Balistes naufragium Jordan & Starks n. sp. PEz 
PUERCO DE PIEDRA. 
Four specimens obtained with dynamite, about the wreck 
of a French man-of-war in the Astillero at Mazatlan, in 
company with Pomacanthus zonipectus. The largest ot 
these was fourteen inches in length. 
Allied to Balrstes carolinensis. 
Head 3; ‘depth 14;\D. [2755 A> 245) scales sone 
rows on cheek; snout 1% in head; eye 5; ist D. spine 
12; longest ray 1; longest anal ray 1%; upper caudal 
lobe 1%; pectoral 2%. 
Body very plump, not strongly compressed; no streaks 
on cheeks; no spinules on caudal peduncle; afew larger 
scutes behind gill-openings; groove before eye, slight 
not naked. Lateral line traceable for most of its length. 
First dorsal spine very stout, the third remote, moderate. 
Dorsal moderately elevated and falcate. Anal rounded. 
Caudal double concave, the pointed outer rays longer 
than the rounded inner ones. 
Dark dull olive green, nearly plain, edges of scales 
