Royal Microscopical Society. 49 



Fig. 4, ptc.) is one bone made up of an endosteal metamorphosis of 

 the cartilage, and the ectosteal transformation of its perichondrium. 

 In the Lizard these parts, like the clavicle and prse-coronoid, are 

 permanently distinct ; other instances in the Lizard's skeleton could 

 be shown. Hence we may see that any hasty interpretation of 

 homologous parts is worse than useless, and that the most delicate 

 microscopic research must go hand in hand with morphology. 



Going forwards to the nasal capsule, we find each " pars plana " 

 (Plate V., Fig. \,p.p.) a large sub-quadrate flap of cartilage, under- 

 going endostosis at its inner edge. The bridge by which this flap 

 passes into the " ali-ethmoid " above is separately ossified, at least 

 it is in Buteo, and the nasal branch of the fifth nerve runs outside it, 

 not through the same passage as the first. The swollen ali-ethmoid 

 (rudimentary upper turbinal) has its own bony tract in old birds. The 

 septum-nasi (Plate V., Fig. 2, s. n.) is well ossified, and is very large ; 

 it ankyloses with the prre-maxillaries and the maxillo-palatine plates in 

 the adult ; in the young the latter union has not taken place : this 

 bird is typically " desmognathous." 



The two-horned " nasals " (Plate V., Figs. 1 and 2) and the 

 lachrymals (I.) are very characteristic ; the lachrymals, besides their 

 long superorbital process, have in the adult a square superorbital 

 hone at its extremity ; this was fibrous in my young specimen. In 

 the Monitor Lizards the whole upper part is super-oxb\in\, and the 

 descending eras or |>r«?e-orbital is the true lachrvmal. 



The " vomer " (Plate V., Fig. 2, v., and Plate VI., Fig. 3, v.) 

 is a long knife-like bar of bone, narrowest in front ; it is wedged-in 

 between the ethmo-palatines (e.pa.). In the adult the vomer is very 

 long and downturned, and enlarged in front, as in Falco and Dicho- 

 lophus, but to a less degree. In Ulula uluco (the Hooting Owl), 

 and in two forms nearly related to this Hawk, namely, Haliastur 

 Indus and Circus cyaneus, there is a " median sep to-maxillary " 

 above the vomer. The vomer is a membrane-bone, and enters into 

 no union with the nasal walls or turbinals. In all Eapacious birds 

 I have found the vomer azygous. Only in Dicholophus is there 

 an " os uncinatum "; it is a rod-like ossicle underlapping the lach- 

 rymal, and standing on the zygoma. 



The palatines (Plate V., Figs. 1 and 2, and Plate VI., Fig. 3, 

 pa.) have a somewhat outspread form. I have not seen a separate 

 " transpalatine " or any cartilage in that region, yet in the 

 European Vulture {Gyps fulvus) the bone is partly separated by a 

 suture from the body of the palatine. The prae-palatine bar is 

 long and lathy; the " interpalatine " spurs aborted; the "ethmo- 

 palatines " are rounded lobes, and the groove between the two 

 inferior ridges behind is of moderate depth. Not in this species, but 

 in several, there is a junction, or " commissure " of the " ethmo- 

 palatines," namely, in Dicholophus; the Owls; Helotarsus ecaudatus ; 

 Sarcoramphus papa ; Neophron percnopterus; Falco tinnuncidus; 



