86 



SCIENCE PROGRESS 



implement the form of the beak of an accipitrine bird. The 

 form of this region of the implement may also be compared 

 to that of the prow of a boat (the boat being turned keel up- 

 wards). If the implement is held with the prow or beak to 

 the front, there are observed an upper or dorsal plane, a lower 

 or ventral plane, a right lateral and left lateral surface, a 

 posterior surface or stern, and an anterior surface, narrowed 

 to the form of a keel and ending in a beak (hence the term 



K£6J~ 



ANT 



Post. 



l£?T U\T6*AV SO*.e*CE.. 



AUT 



ANT 



~~KS.eL 



?OST 



Post 



Fig. A. 



" rostro-carinate ") as a consequence of the oblique direction 

 and convergence of the lateral surfaces, which approach one 

 another so as to leave only a narrow keel-like ridge between 

 them (see fig. A). It is proposed to indicate in each text figure 

 the anterior (ant) and posterior (post) region of each specimen 

 portrayed. The upper, dorsal surface, and the lower, ventral 

 surface, will be indicated by the letters D.S. and V.S. respec- 

 tively, while the left lateral surface (L.L.S.) and the right 



