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PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 43. 



as long as snout, tip reaching beyond origin of anal; pectoral equal 

 to snout in length. 



Color in alcohol: Hair-brown; belly, base of fins, and branchi- 

 ostegal membranes darker. 



Type.— C&t. No. 72945, U.S.N.M., 32 cm. in length, taken with a 

 beam trawl at station 5348 (lat. 10° 57' 45" N.; long. 1 18° 38' 15" E.), 

 in Palawan Passage, at a depth of 375 fathoms, on a bottom of coral 

 sand. 



The type form (fig. 2) is at once distinguished from C. macrorhyn- 

 chus by the much shorter and broader snout and large eye. It 

 differs from C. japanicus (Sclilegel) in the following characters: Dor- 

 sal rays 8 or 9 (9 or 10 in japanicus); lateral outline of snout con- 

 vex (instead of straight); 5 or 6 scales from origin of dorsal to and 

 including lateral line (instead of 6 or 7); 5 to 7 radiating ridges on 

 scales (instead of 3 to 5). The anal rays in japanicus are much 

 better developed than in this species. 



Our examples of the present species, while fairly constant as far as 

 scaling, form of fins, and body are concerned, nevertheless fall quite 



Fig. 3.— CtELOEHTNCHUS COMMUTABILIS, FORM ALPHA. 



readily into one of several groups, each of which, had it been found 

 alone in a separate locality, would have been regarded without doubt 

 as representing a distinct species. The main points of difference of 

 the typical examples of each group lie in the form, length, and scaling 

 of the snout. As the tail is as often mutilated as complete and as a 

 lengthened or shortened snout renders comparative measurements 

 in terms of head of little or no value, the ordinary standardization of 

 measurements does not serve as a satisfactory means of separation. 

 That there is evidence of mutation seems quite certain, and the 

 nature of the organism appears to have been a more important factor 

 than environment in effecting these changes. We have described as 

 the type the form which appears to be predominant; the others are 

 described below as forms alpha, heia, etc. There are 19 examples of 

 the predominant form from depths of 220 to 375 fathoms. 



Form alpha. — ^Differs from typical comTnutahilis in having a shorter 

 and broader snout, its length 2.50 to 2.80 in head (2.14 to 2.45 in 



