PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 287 



The shape of the body resembles that of A. nigricans; the caudal, 

 however, is emarginate and not deeply forked as in that species. 



In the description and table of measurements the length of body is 

 to be understood to mean the length to the origin of the middle caudal 

 rays — 57.2 inches. 



The greatest height of the body (.20) is contained 3J times in its 

 length, and equals twice the length of the external caudal rays (.14). 

 Its greatest width (.18) is contained 5^ times in length of body, and 

 equals | of the length of the head (.27). The height of the body at the 

 ventrals (.29) equals the greatest height. The least height of the tail 

 (.081) equals the length of the snout (.084), which is contained 3^ times 

 in the length of the head- The length of the caudal peduncle (.16) 

 equals twice its least height. 



The length of the head (.27) is contained 2§ times in length of body, 

 and equals 3 times that of the ventral (.09). The width of the mouth 

 (.168) equals twice the length of the snout (.084), and is contained 6 

 times in length of body. The extent of the intermaxillary band of 

 teeth (.106) nearly equals the distance from the snout to the orbit (.108). 

 The greatest width of the head (.22) equals | of its greatest length. 

 The distance between the eyes (.15) is slightly more than half the length 

 of the hea^l, and equals the length of the mandible (.15). The length of 

 the intermaxillary (.108) equals the distance from the snout to the orbit 

 (.108), and is contained 2i times in the length of the head. The length 

 of the maxillary barbel of the right side (.16) equals that of the caudal 

 peduncle, and uearlj^ equals the width of the mouth. The remaining 

 barbels except the nasal are too imijerfect to admit of description. The 

 distance fi'om the lower nostril to the eye (.06) equals 4 times the long 

 diameter of the eye (.015). The distance from the upper nostril to the 

 eye (.056) is contained slightly more than 4^ times in the length of the 

 head. 



The distance of the first dorsal from the snout (.365) is contained 2f 

 times in length of body, and equals 3 times the length of its first ray 

 (.122). The length of the first dorsal base (.082) nearly equals that of 

 the snout. The length of the dorsal spine (.105) is contained 2 J times 

 in that of the head. The length of the last dorsal ray (.05) equals ^ of 

 the distance between the eyes. 



The distance of the adipose dorsal from the snout (.81) equals nearly 

 3 times the length of the head. Its length of base (.043) is contained 

 6 times in the distance of the pectoral from the snout (.26). Its greatest 

 height (.00) equals the distance between the lower nostril and the eye 

 (.06), and is contained 4.} times in the length of the head. 



The distance of the anal from the snout (.67) is contained li times in 

 length of body, and equals 3 times the greatest width of the head ; its 

 distance from the anus (.035) is contained 3 times in the length of the 

 dorsal spine, and 8 times in that of the head. The length of the anal 

 base (.26) equals the distance of the pectoral from the snout (.26), and 



