470 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



4.15 (4.2) times in the head, extends backward almost to below the 

 hinder margin of the pupil. The outer series of premaxillary teeth 

 are scarcely enlarged. The free portion of the small barbel is con- 

 tained but 7.2 (6.2) times in the postorbital. The gill-membranes 

 cross the isthmus with a narrow free fold; six branchiostegals. 



The center of the anus is distant from the anal, the interspace being 

 half the distance from the anus to the base of the outer ventral ray, 

 a distance which is contained 1.2 times in that between the ventral 

 and the isthmus, or 1.3 (1.4) times in the postorbital. There is no 

 trace of a ventral fossa in front of the anus nor between the ventrals. 



The scales are smaller and more closely imbricate than in the fol- 

 lowing species, there being 6^ in a series from the origin of the 

 second dorsal fin to the lateral line series. The scales are less strongly 





Fig. 13. — Coelorhynchus dorsalis. Type. 



spinous than in argus and macrolepis, but their carinae are more dis- 

 tinctly developed, numbering 8 to 11 on each scale (5 to 7 in the 

 smaller paratype). Each of the carinae bears 12 or fewer short, 

 sharp, close-set spinules directed backward, the last one projecting 

 slightly beyond the margin of the scale. In general the squamation 

 of the head is similar to that of notatus, seocradiatus, and triocellatus, 

 but a few differences are apparent : the carinae on most of the scales 

 of the head are similar to those of the body ; they are usually more 

 divergent, weaker, and smoother than in the preceding species. The 

 dorsoterminal plate is shorter than in trioceUatus but more prominent 

 than in notatus and sexradiatus; its dorsal length is contained 3.3 

 .times in the postorbital (4.1 times in the paratype). Seven scales 

 cover the ethmoid portion, and 10 or 11 (9) the preorbital portion 

 of the infraorbital ridge. Over the mediorostral ridge there are but 

 8 narrow scales, each more oval than in the preceding three species, 

 and armed with spinous carinae radiating from near the center of 



