200 



COMPARATIVE ANATOMY. 



in Crocodiles an intermediate condition between Birds and 

 Lizards is seen. The membranous labyrinth of Birds, however, is 

 always specially characterised by the peculiar arrangement of the 



Cm 



FIG. 163. MEMBRANOUS LABYRINTH OF Lacerta. 



SB 



FA- 



FIG. 164. MEMBRANOUS LABYRINTH OF THE CROCODILE. (Both from the outer 



side.) (After C. Hasse.) 



S, sacculus ; ut, utriculus ; Re.ut, recessus utrbuli ; VR, connecting-duct of the 

 posterior ampulla ; SB, FB, HB, anterior and posterior vertical, and horizontal 

 canals, with their ampullae (SA, FA, and HA) ; Co. commissure of the vertical 

 canals ; pb, pars basilaris cochleae : pi, macula acustica neglecta ; lag, lagena ; 

 N, auditory nerve. 



anterior and posterior canals, which are greatly arched, and the 

 position of the openings of which into the sinus superior (canal 

 commissure) is reversed. 



In lower types (Swimming Birds) this peculiarity is less marked than in the 

 higher forms, and it would be very interesting to ascertain the condition of 

 these parts in the Struthionideo, as one would expect to find in them important 

 points of connection with Reptiles. 



In spite of this higher stage of development of the auditory 

 organ in Crocodiles and Birds, we cannot speak of the presence 



