424 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



The lining of the buccal and branchial cavities is blackish, except 

 along the margin of the mouth; the peritoneum is blackish brown, 

 underlaid with silvery. 



Table of measurements in hundredths of length to anus. 



A Ibatross station 



Total length in mm 



Length to anus in mm 



Length of head 



Length of orbit 



Width of interorbital 



Width of suborbital 



Orbit to preopercle 



Length of snout 



Width of snout 



Length of upper jaw 



Length of barbel 



Depth of body 



Width of body 



Anal to anus 



Anus to ventral , 



Ventral to isthmus 



Height of second dorsal spine 



Height of third dorsal ray 



Length of first dorsal base 



Length of interdorsal space 



Length of pectoral 



Length of outer ventral ray '. 



Length of second ventral ray 



'A pseudocaudal developed. 



(hyostomus, meaning hog-mouth.) 



5467 

 '259 



71 



74 



18 



16.5 



11 



29 



25 



28 



21 



•6 



47 



29 



15 



20 



23 

 163 



Genus COELORHYNCHUS Giorna. 



The fauna of the Philippine Islands and the adjacent region to 

 the southward has proved to be exceptionally rich in the species of 

 Goelorhynchus. The region appears to be the center of their dis- 

 tribution, for in no other similar area in any of the seas is there 

 known anything like the variety of species which occurs there. Of 

 special note are the numerous species of the C. notatus and the 

 G. japonicus groups. The subgenus Quincimcia is unknown else- 

 where. In this region there are now known 23 species, or 45 per 

 cent, of the total number in the world. 1 Despite the occurrence of 

 this large number of species, none of them, with the exception of 

 G. parallelus, has been discovered in other faunal regions, although 

 some of them have close representatives in the Indian, Japanese, and 

 Hawaiian faunas. These facts of distribution have already been 

 discussed in the introduction. 



The following analytical key has been arranged, as far as possible, 

 to indicate the mutual relationships of the subgenera and species, 

 each one being most closely related to the group or species preceding 

 and following; it. 



1 The authors have examined 42 of the 51 known species. 



