510 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the lower half of the nasal fossa, and the region below the orbit, 

 extending backward to the preopercular ridge, are reduced in size, 

 but usually bear divergent ridges; the five series of scales between 

 the occipital ridges converge backward toward the median occipital 

 scute, which is variously armed by a single median keel or by 

 several divergent ridges; a somewhat similar scute is located at the 

 origin of the lateral line. The scales between the occipital and post- 

 orbital ridges are in about five series, and bear several carinae; 

 those scales forming the median series are markedly enlarged, those 

 in the next series below the median are scarcely reduced, those in 

 the first series above the median are small, those in the two or three 

 other series are reduced in size. In G. japonicus the scales of the 

 head are quite different; they are smaller, as a rule, and even in 

 specimens considerably larger than any known of C. commiitdbilis 

 mostly bear only a single spinous crest, except on the scaly ridges 



Fig. 



29. COELORHYNCHUS COMMUTABILIS. AFTER RADCLIFFE (" COELORHYNCHUS 



COMMUTABILISj FORM ALPHA"). 



and in the median series between the occipital and postorbital ridges. 

 The underside of the head in both species is constantly covered by 

 small scales. 



Pyloric caeca, 20 in one specimen, 28 in another (50 were counted 

 in a specimen of C. japoiilcus): 



The height of the second dorsal spine in contained 2.1 (1.85 to 2.1) 

 times in length of head ; its length when laid out on the head from 

 the opercular angle extends forward to the front of pupil (in para- 

 types varying forward and backward from that point a distance 

 almost as great sfs the diameter of the pupil). The length of the 

 first dorsal base is contained 1.63 (1.35 to 1.75) times in the interval 

 between the dorsals, and 2.1 (1.7 to 2.1) times in the postorbital 

 length of head. The outer ventral ray, ending in a slender filament, 

 is contained 2.65 (2.1 to 3.0) times in head; the second ventral ray, 3.7 

 to 4.35 times, not reaching to the anus. 



Color in alcohol grayish broMm, of varying shade, becoming 

 lighter below ; darker and less silvery than in G. radcMffei, less 

 brownish than in G. smithi. The fins are blackish, varying to light 



