118 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



with dark punctulations ; photophores surrounded by dark color, and 

 often with narrow black ring extending across upper part of some of 

 the organs; dorsal, caudal, and anal somewhat dusky; other fins pale. 



One specimen about 47 mm. (40 mm. to base of caudal) long, was 

 taken by the Mission in a surface net at latitude 4°24' S., longitude 

 81°35'45" W., that is, off northern Peru. This specimen agrees well 

 with the original description and figure of the type of M. teniculum, 

 though the minute light organ at angle of mouth is not evident in the 

 specimen herein described. 



M. teniculum was synonymized with M. coccoi Cocco by Parr (see 

 reference above). However, the specimen at hand, and evidently 

 the type also, differ in so many respects from specimens of M. coccoi 

 (U.S.N.M. No. 100470), from the vicinity of Bermuda, that I hesitate 

 to follow Parr. If they are identical, greater variation than ordinarily 

 exists among specimens of one species would have to be admitted. 

 The body in the Peruvian specimen is much deeper, the head is longer, 

 the anal and ventral rays are fewer, and the gill rakers on the upper 

 limb of the first arch are more numerous. The following proportions 

 and enumerations are based on four specimens, 40 to 60 mm. (36 to 

 43 mm. to base of caudal) long, from the Atlantic: Head 4.3 to 4.6 

 in length; depth 4.9 to 5.3. A. 21 or 22; V. 8; gill rakers 3 or 4 + 7 or 

 8. It is not evident from the literature consulted that the differences 

 shown are covered by individual variation. 



Range. — Panama to Peru. Pelagic. 



MYCTOPHUM AFFINE (Lutken) 



Scopelus affinis Lutken, 1892, p. 252, open Atlantic (original description). 

 Mydophum affine Parr, 1928, p. 69, fig. 8, Atlantic, Pacific, and Indian Oceans 

 (synonymy; discussions; tables). 



Head 3.6; depth 4.15; D. 13: A. 18; V. 8; P 12; scales 37. 



Body rather deep, compressed, its greatest thiclaiess half its depth, 

 tapering posteriorly; peduncle only moderately slender, 3.5 in head; 

 head moderately short, compressed; snout blunt, 8.2 in head; eye 2.9; 

 interorbital forming a shelf over eyes, 3.4; mouth oblique, terminal; 

 maxillary narrow, extending well beyond posterior rim of orbit, 1.5 

 in head; teeth as in M. teniculum; lateral line complete, little decurved; 

 photophores in a more or less continuous row along ventral edge of 

 trunk and taU, 5 in advance of ventral fin, 4 between ventral fin and 

 origin of anal, and 14 from origin of anal to base of caudal; a long space 

 between the last organ in advance of anal and the first opposite base of 

 anal, a somewhat shorter interval between the seventh and eighth 

 organs along base of anal, and a similarly long space separating the 

 last two organs on base of caudal; 2 large light organs on median 

 ventral line of peduncle; 3 along lower jaw; 1 on interorbital; 1 

 behind preopercular margin, 1 above and 1 just below base of pectoral, 



