Contributions to Bird-Anatomy and Classification. 23 



but must form an independent group of birds, having probably 

 " sprung from the primary avian stock as an independent 

 offshoot at much the same time as did most of the other im- 

 portant families/^ 



8. Ararnus^-. — In the schizorhinal character of its skull, as 

 well as in the presence of occij)ital foramina, Aramus resem- 

 bles Grus, Ibis, Platalea, and the Limicolse, and not the Pal- 

 lidas, with which it had generally been associated previously ; 

 and this collocation is quite confirmed by its myology and 

 visceral anatomy. 



9. Plot/isf. — In the first paper the anatomy of P. anhinga 

 is described at considerable length — particular stress being 

 laid on the curious arrangement of the cervical vertebrae which 

 makes this bird literally unable to carry its neck straight, and 

 the correspondingly modified muscular system. Other points 

 described are the presence of but one carotid artery, and 

 of but one ciecum — the latter a feature previously unknown 

 in any Steganopodous bird, though constant in the Herons. 

 The most interesting feature, however, of Plotus anhinga is its 

 very extraordinary stomach, previously only partially described 

 by Macgillivray. The proventriculus, instead of forming a 

 zone or patch, is here developed into a special sac-like diver- 

 ticulum, which projects from the gizzard externally in a way 

 quite unlike that of any other bird. Moreover the pyloric 

 compartment of the stomach, which is present in a less com- 

 plete form in Pelecanus, the Herodiones, Falconidse, &c., liere 

 develops a covering of hairs, '' a peculiarity which, as far as 

 I know, is found only in one other bird, namely Cathartes 

 aura.'' This very extraordinary stomach is figured on plate 

 xxviii., and is certainly, as far as yet known, unique amongst 

 birds. In Plotus levaillanti the same features in its anatomy 

 generally are present as in P. anhinga. But there are, as 

 usual, two small caeca : and its stomach differs considerably ; 

 for here there is no proventricular gland-pouch, but this 



* " On tlie Anatomy of Aramus scolopaceus,''^ P. Z. S. 187G, pp. 275-277. 



t " Notes on the Anatomy of Plotm anhinga,'^ P. Z. S. 1876, pp. ^35- 

 345, pis. xxvi.-xxviii. '; " Note on Points in the Anatomy of Levaillant's 

 Darter (Plotus levaillanti);' P. Z. S. 1878, pp. 679-681. 



