488 CALIFORNIA ACADEMY OF SCIENCES. 



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 Prioniirus by the 

 armature of the caudal peduncle, as above described. 



Family BALISTID^. 



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 Poniacant/uis zonipectus. The largest of 

 these was fourteen inches in length. 



Allied to Balistes carolinensis. 



Head 3; depth i|; D. III-27; A. 24; scales 50; 12 

 rows on cheek; snout i^ in head; eye 5; ist D. spine 

 i|; longest ray i^; longest anal ray i^; upper caudal 

 lobe i>^ ; pectoral 2^. 



Body very plump, not strongly compressed; no streaks 

 on cheeks; no spinules on caudal peduncle; a few 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 



