1889.] THE BODY-CAVITY IN LIZARDS, ETC. 467 



as being very peculiar ; but it is led up to in other genera of the 

 Teiidae. Thus, in Ameiva and Callopistes the median ventral liga- 

 ment is, as it were, expanded laterally behind the liver, or it may be 

 said to give oif at right angles on either side a membrane which 

 dorsally becomes attached to the hinder part of the liver. 



]n Ameiva and Callopistes, however, the transverse vertical septum 

 thus formed is not continuous with the lateral walls, and there is a 

 free passage on either side. Bvit in Tvpinambis (see Plate XLVIII. 

 fig. 32, which is a view of the septum from behind, ventral side 

 uppermost) the subdivision of the body-cavity is much more com- 

 plete. On the right side there is only a very small aperture of 

 communication (o) between the pulrnohepatic and intestinal cavities. 

 This is situated on the dorsal side external to the inferior vena cava 

 and the attenuated extremity of the right liver-lobe, which is repre- 

 sented as visible through the septum. On the left side there is a 

 larger, but still comparatively small, aperture (o') also dorsally 

 situated. 



Figs. 33 & 34 give side views, ventral side uppermost, of this 

 post-hepatic septum (/3), and the organs contained in the pulrnohepatic 

 cavity in front of it. The whole lateral body-wall next the observer 

 is supposed to be removed. In fig. 31, on the right side (left of 

 observer), only the ventral part of this septum is displayed, the more 

 dorsal part lying concealed beneath this, together with the extremity 

 of the right liver-lobe. 



This post-hepatic septum I have throughout indicated by the same 

 letter (J3) as the more ventral, or omental, part of the post-hepatic 

 septum of birds, in accord with my opinion that they are homologous ; 

 since the position of the foramen of either side seems to make it clear 

 that there is no component growing in from the dorsal side corre- 

 sponding to the oblique abdominal septum of the bird. This is just 

 what we should expect, there being no development of abdominal 

 air-sacs. 



The difference between the adult condition of these Teiidce and 

 that of the other type of Lizard would seem to imply that the vena 

 cava inferior of the former, instead of developing, as in Lacerta, 

 Gallus, and Lepus, in tissue continuous with the posterior part of the 

 pulrnohepatic ligament, has arisen in a lateral transverse outgrowth 

 of the dorsal part of the longitudinal median septum or mesentery, 

 in fact in a membrane situated altogether posterior to the place 

 where the pulmohepatic recess would lie if present. 



The need of some such transverse membrane, in the absence of the 

 pulmohepatic ligament, to carry the vena cava inferior to the liver, 

 accounts for the dorsal portion of the post-hepatic septum in the 

 TeiidcB. 



To the relations of the lungs in the Teiidse I have already referred 

 (p. 465). 



V. On the Body-cavity of the Crocodilia. 



Turning now to the Crocodiles. In the absence of any data as to 

 the development of the septa in these animals (such as we possess in 



