1 82 PATAGONIAN EXPEDITIONS: PALEONTOLOGY. 



HAPALOPS LONGICEPS sp. nov. 



(Plates XXX-XXXIII.) 



This is one of the largest known species of this variable genus and is 

 characterized by the great elongation of the rostrum ; the premaxillaries 

 and the edentulous beak of the mandible being much longer than in any 

 other known species. The species is described first, because the type- 

 specimen (No. 15,523) is much the most complete single individual that 

 has yet been found and forms a convenient standard of reference for the 

 other species. 



Dentition (Plates XXXI, figs. 1,2; XXXII, fig. 2). The teeth dif- 

 fer but little from those of the other representatives of the genus ; - is, 

 as usual, small, caniniform, obscurely trihedral, inserted just behind 

 the maxillo-premaxillary suture and separated from - by a considerable 

 diastema. The other upper teeth ( ) are molariform ; - is subquadrate, 

 with rounded angles; * is considerably larger and more trihedral, - is 

 more rectangular and - is very small, obliquely worn and without trans- 

 verse valley ; on the posterior face of A is a shallow, vertical groove, which 

 causes a faint bilobation. 



In the lower jaw T is caniniform, but smaller than - and more erect, 

 rising higher than the other mandibular teeth, and separated from ^ by a 

 shorter diastema than that of the upper jaw ; ^ and are transverse and 

 rectangular, and their raised margins are quite deeply notched on the 

 inner and outer sides by the transverse valley ; T is subcylindrical, as in 



most of the other species. 



MEASUREMENTS. 



Upper dentition, length 058 , width 008 



" ^ 035 Lower dentition, length 044 



Diastema, length 015 " " " 577 029 



1, length (i. e. ant.-post. diameter) 008 Diastema, length 012 



" width (i. e. transverse diameter) 007 T , length 006 



, length 007 " width 005 



" width oio y, length 0075 



*-, length 008 " width 0105 



" width oil j, length 0085 



A, length 007 " width oio 



" width 0105 j, length 009 



, length 0055 " width oio 



Skull (Plates XXXI, XXXIII, fig. i). When seen from the side, the 

 skull is long and low; its upper contour rises quite steeply from the 



