304 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



Amiuxus Dugesii Bean, sp. nov. 



This species is allied to A. albidus (Le Sneiir) Gill, but has a much 

 narrower head as is shown in comparing- the width (greatest extent) of 

 the intermaxillary band of teeth in the two species. The head of 

 A. Dugesii is also longer in i)roportion to the length of the fish without 

 caudal, and the humeral process is slightly furrowed, and not strongly 

 rugose as in A. albidus. The pectoral spine is not serrate. Amiurus 

 Dugesii has the supraoccipital well separated from the second inter- 

 spinal buckler. 



The typical specimens are numbered 23122 and 23123 in the Fish 

 Catalogue of the Museum. They were received from Prof. A. Duges in 

 June, 1879, and were marked in his invoice as coming from the Eio 

 Turbio in the province of Guanajuato, Mexico. 



Description. — The height of the body is contained 4J to 5 times in 

 its length without caudal. The distance from the end of the anal to the 

 origin of the middle caudal rays is a little more than half the length of 

 the head. 



The length of the head (.29) exceeds its greatest width (.21-.23) by 

 one-third. The maxillary barbel can be made to reach the pectoral 

 spine, and is contained 5 times in the length of the body. The distance 

 between the eyes (.125) equals 4 times their long diameter (.03). The 

 length of the snout is about ^ of that of the head (in the smaller exami^le 

 somewhat less). The width (greatest extent) of the intermaxillary band 

 of teeth (.095) is less than ^- of the length of the head (nearly ^ in A. 

 albidus). The length of the maxillary (.04:-.045) is about ^ of the inter- 

 orbital distance. The posterior nasal barbel is a little less than ^ as 

 long as the maxillary barbel. 



The first dorsal begins midway between the end of the snout and the 

 beginning of the adipose dorsal. The length of its spine is about equal 

 to the length of the base of the adipose dorsal. Its longest ray is con- 

 tained to 7 times in the length of the body. 



The distance of the anal from the snout equals 3 times the length of 

 its base. The longest anal ray is as long as the ventral. 



The middle caudal rays are one-half as long as the external, measur- 

 ing from the origin of the former. 



The distance of the pectoral from the snout (.26-.27) equals one-half 

 that of the ventral from the snout. The length of the pectoral spine 

 is contained 2^ times in that of the head. The longest pectoral ray 

 (.15-.1G) is a little more than ^ as long as the head. 



Radial formula: B. VIII; D. I, 6; A. 21-22; C. 17 (developed rays) ; 

 P. I, 8; V. I, 7. 



The lateral line is almost complete. 



Colors : Plumbeous above, silvery white beneath and on the sides. 



