OF THE RED CRAG. 



23 



tract simulates a sutural division of the tract itself; but the one is due to fracture, aud the 

 other to a linear groove, which groove gradually becomes shallower, and is obliterated at six 

 and a half inches from the internarial part of the prefrontal. The linear grooves (22, 22, 

 fig. 3) dividing the mid-tract from the lateral parts of the premaxillaries disappear about 

 the same part of the snout with such mid-groove. The ectomaxillary ridge (e, e) rather sud- 

 denly decreases about three inches from its basal beginning, but is continued forward four 

 inches before it finally subsides ; a narrow groove extends forward in the same direction to 

 the fractured fore end of the snout. The median fissure between the descending pterygoid 

 plates is conspicuous in the present species ; they seem not to have coalesced so completely 

 as in the palatal carina so formed in previous species. An inferior median ' vomerine' 

 tract is indicated by pai-allel longitudinal grooves along the anterior two inches of the 

 palatal surface of the present specimen. The constituents of the rostrum at this part are 

 marked in fig. 10 by the same numerals as in fig. 9. 



