178 MR. W. P. PYCEAFT ON THE MORPHOLOGY AND 



in the Dinornithidce as the vertical plate dividing the pre-sphenoid fossae. There is a 

 well-marked supraorbital fenestra. 



The Dinornithidce are apparently peculiar in the development of a pair of well- 

 developed triangular processes, forming a horizontal plate projecting from the ventral 

 border of the mesethmoid, and extending outwards to the level of the lachrymal. 



In Apteryx the ossified ectoethmoidal plates form two oblong, much inflated bullae 

 on either side of the head, nearly filling up the very small orbit, the horizontal plates 

 of the mesethmoid sweeping outwards, downwards, and inwards, the ventral edge 

 fusing with the mesethmoid immediately above the parasphenoidal rostrum. Forwards, 

 the part corresponding to the antorbital plate affords support to the lachrymal, as in 

 Dromceus. 



As the late Prof. T. J. Parker has pointed out [71], "One of the most striking 

 characteristics of the skull of Apteryx is the extreme complexity of the turbinals. When 

 the mesethmoid is removed there are seen in the olfactory chamber proper four well- 

 marked obliquely vertical folds, while a fifth is continued into the narrow or respiratory 

 portion of the nasal cavity. The three hindmost of these folds are perfectly distinct 

 one from another, and I propose to call them, respectively, the anterior, middle, and 

 posterior turbinals. The fourth and fifth folds are intimately connected with the 

 anterior turbinal : I call the uppermost of the two, which forms part of the olfactory 

 region, the anterior accessory turbinal, and that which extends forwards, and has no 

 olfactory function, the ventral accessory turbinal. 



" All the turbinals, with the exception of the ventral accessory, are covered by 

 Schneiderian membrane, and are therefore analogous to the ethmo-turbinals of a mammal. 

 The ventral accessory turbinal is covered with ordinary mucous membrane, and belongs 

 to the merely respiratory portion of the nasal chamber ; it may be compared with the 

 maxillo-turbinals of mammals. 



" On each side of the ventral edge of the mesethmoid, in the vomerine region, 



is a slender rod of cartilage, imbedded in connective tissue, and lying parallel to, and 

 either immediately dorsad or slightly laterad of the dorsal edge of the trough-like 



vomer it can be readily prepared in a well-macerated skull by carefully 



removing the vomer. It is obviously the vestigial cartilage of Jacobson's organ . . ." 



The ventral accessory turbinal does not appear to ossify in the adult Apteryx skull. 



There are no ossified turbinals in the other Palceognathce. 



The lachrymal in Casuarius is crescentic in form, with convex border forwards. 



Its upper limb, when visible, is very broad and deeply notched. It forms a broad 

 overhanging ledge to the orbit. Its lower limb is flattened from before backwards and 

 extends downwards to within a short distance of the quadrato-jugal bar. At the 

 junction of the upper and lower limbs it is perforated by a large foramen for the 

 passage of the lachrymal duct. In the adult, the inferior inner lateral border is fused 

 with the antorbital plate. 



