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PR0CEEDI2SrGS OF THE NATIONAL MUSEUM 



VOL. 88 



M. macrocephalus); the wider interorbital space (2.0 to 2.4 in M. 

 cavernosus, 2.6 to 3.0 in M. macrocephalus) ; and by the shorter max- 

 illary (ending below the middle of the eye in M. cavernosus and beyond 

 a vertical from the posterior margin of the eye in M. macrocephalus). 

 From AI. microps ^ this species is separated by the deeper body 

 (3.2 to 3.4 in length without caudal from M. cavernosus, 4.75 to 5.0 

 in M. microps); the wider interorbital space (2.0 to 2.4 in head in 

 M. cavernosus, 3.0 to 3.25 in M. microps); the shorter maxillary (end- 

 ing under the middle of the eye in M. cavernosus, under or beyond the 



FiGUKK 6S.—Metamphae3 cavernosut, new species: Holotype (U.S.N.M. no. 108147), 70 mm long, from 



station 824C. 



posterior margin of the eye in M. microps); more rays in the pectoral 

 (15 to 16 in M. cavernosus, 14 in M. microps); longer caudal peduncle 

 (3.7 to 3.9 in length without caudal in M. cavernosus, 4.25 to 4.5 in 

 M. microps). From the subspecies M. microps longivelis, described 

 by Parr (1933), this species is easily told by the longer caudal peduncle 

 (3.7 to 3.9 in length without caudal in M. cavernosus, about 5.0 in 

 the other). 



This species is distinguished from AI. lugubris ^ by the greater 

 number of scales in a longitudinal series (29 to 31 in M. cavernosus, 

 26 to 27 in M. lugubris); by the wider interorbital space (2.0 to 2.4 

 in head in M. cavernosus, 3.0 in AI. lugubris) ; shorter maxillary (ending 

 under middle of eye in AI. cavernosus ending below posterior border of 

 eye in AI. lugubris); wider pectoral fin (16 rays in AI. cavernosus, 14 ? 

 in AI. lugubris); longer caudal peduncle (3.7 to 3.9 in length without 

 caudal in AI. cavernosus, 5.0 in AI. lugubris); and in the position of the 

 origin of the pelvics (behind the insertion of the pectorals in M. 

 cavernosus, ahead in AI. lugubris). 



The portion of the key to the species of this genus, published by 

 Norman (1929) and added to by Parr (1931 and 1933), deaUng with 

 the above species should be modified as follows in order to accom- 

 modate this new species: 



• Measurements from Norman, 1929. 



