108 MR. W. K. PARKER ON THE STRUCTURE 



The development of the preoral arches and nasal capsule in the " Pringillidae " (which 

 in the person of the Sparrow gives name to the group) will show the peculiarities of this 

 type, a type which takes in all Professor Huxley's " Coracomorphse " {op. cit. p. 469), 

 the Swifts amongst his " Cypselomorphae " (p. 468), and the Hemipods also, which lie 

 down lowly, in an ornithic stratum immediately over the " Tinamidse" *. 



In embryos of the Brown Linnet {Linota cannabina), at about the end of the fifth 

 day of incubation, I find the facial arches and nasal capsules (Plate XXI. figs. 1 & 2) 

 in a very instructive condition. Nearly the whole of the long " trabecular commissure " 

 is shown, the bar being severed in the prepituitary region, where the ethmoid and basi- 

 sphenoid meet; the prenasal rostrum (jm) is in full size, as the continuation of the 

 great cartilaginous balk. 



This balk is wasting between the ethmoidal and septal regions, preparatory to its 

 peculiar ornithic segmentation. 



The open or naturally cloven state of the palate is here shown ; for the folds of the 

 nasal labyrinth are well seen below, and the " median nares " {mn) are large and 

 patulous. Neither the true olfactory nor the inferior turbinal regions are displayed in 

 this figure, only the immensely developed alinasal structures, so very secondary in 

 importance and size in the Mammal. The trabecular being bowed and folded over in 

 front send backwards, on each side, a flap of cartilage ; this may be called the " recur- 

 rent fold " {rcc). These two flaps form a commissure below the fore end of the 

 septum nasi ; and this becoming ossified from the alar, sometimes appears as an anterior 

 nasal bridge, a desmognathic band close behind the fore beak (e. g. in Ditfiolophus). 



Tbe posterior of the three folds, the inturned lamina {ial), seen in the preparation, is 

 the swelling alinasal wall passing into the floor of the nasal vestibule. Here it is far in 

 front of the maxillo-palatine hook {mxp) ; but after a short while it will lie on this bony 

 bar, and become intimately connected with it by the binding fibres belonging to each 

 structure. Between the plaits already described is seen a middle cartilage ; this is an 

 outgrowth of the wall or posterior plate. It is the alinasal turbinal, and ends in a 

 double free edge. 



Although the premaxillaries {px) and maxillaries {mx) are already well developed, yet 

 one does not see here the broad forked vomer of this type. Looking, however, carefully 

 between the wasting middle bar and the inturned alinasal wall {ial), there is to be seen 

 at this stage a small oval cartilage ; as this appears to me to be as yet undescribed, I 

 propose to call it the " vomerine cartilage" (vc). It ossifies endosteally, and has even 

 now a small core of osteoblasts with the finest deposit of calcareous matter. One of these 

 cartilages is more highly magnified in fig. 2, and also with it part of the nasal wall, ali- 

 nasal turbinal, and maxillo-palatine. 



This cartilage is small here in the Linnet, but very large, as I shall soon show, in 

 other " iEgithognathar ;" and as it forms the mother patch for each vomerine moiety, it 



* In the paper under notice (p. 459) Professor Huxley placed the Hemipods among the Fowls, " Alectoro- 

 morphge ;" but in another equally important contribution to Ornithology, namely, his " Classification and Distribution 

 of the Alectoromorphse " (Proc. Zool. Soc. 1868, pp. 294-319), he places the Hemipods apart, having gained a clearer 

 insight into their peculiar characters (see p. 304). They are now his " Turnicimorphse." 



