182 Macieay Memortat Vouume. 
throughout this paper, consisting chiefly of the premaxillary bones which turn 
inwards abruptly in front—forceps-like—to limit the bony rostrum anteriorly, while, 
in the hinder part of each crus, the premaxilla is wedged in between, and supported 
by, the splint-like forward (rostral) prolongations of the nasal and superior maxillary 
bones, internally and externally respectively. 
A very extensive open gap which we may call “inter-crural” is thus included 
between these rostral crura. This interval is open in front between the forceps-like 
points which do not approximate very closely to one another. Viewed from the 
dorsal aspect this interval narrows posteriorly into a mere notch between the nasal 
bones where it limits the incomplete bony anterior narial aperture which is partially 
divided by the incomplete bony septum. 
Viewed from the ventral or palatine aspect (fig. 17) the same area is visible, open 
in front, and bounded laterally by the same diverging bony crura (of which, however, 
the nasal component is not here visible, bemg confined to the dorsal aspect), but 
truncated posteriorly because bounded by the abrupt, notched, anterior margins of 
the palatine processes of the superior maxillary bones. The presence of a notch on 
the anterior border of each palatine process gives rise to the appearance of a mesial 
tongue-like process projecting into the hinder angle of the wide inter-crural space. 
The anterior margin of this tongue of bone is abrupt and is in relation with the 
hinder end of the dumb-bell-shaped bone. 
This so-called dumb-bell-shaped bone was originally regarded by Rudolphi (8), 
Meckel (9) and Owen (10) as the equivalent of an inner division of the inter-maxillary 
bones. Then Owen (11), followed by Flower (12), interpreted it as the homologue 
of the prenasal of the pig. But more lately Albrecht (13) and Turner (14) have 
shown that the original view is the more correct one, and this finding has been 
adopted by Flower and Gadow (15), and more recently confirmed by Symington (16). 
The last-named author concludes that “the dumb-bell-shaped bone from its 
position in relation to the cartilages of the nose is evidently ossified in the membrane 
investing them.” 
With the exception of Symington, none of the authors referred to seems to have 
investigated the constitution and connections of the cartilaginous walls of the nasal 
cavities in this region with special reference to their intimate relation to the dumb-bell- 
shaped bone. Symington, indeed, has accurately described and figured the construc- 
tion and disposition of the nasal cartilages in the immediate neighbourhood of the 
dumb-bell-shaped bone and has arrived at the conclusion quoted above from his work. 
He has also stated in outline the constitution of the nasal capsules in front of the 
dumb-bell-shaped bone. There are, however, some points of importance in the 
