472 MR. G. W. BUTLER ON THE SUBDIVISION OF [NoV. 19, 



ventral portion of the Mammalian diaphragm. Doubtless the re- 

 sults of the systematic research he is undertaking will be of the 

 greatest interest, but it is only necessary for me here to refer to cer- 

 tain points in his nomenclature. 



Ravn calls the membrane passing between the lung and the liver- 

 lobe of the right side (the pulmohepatic ligament of this paper) the 

 ligamentum pulmonale accessorium. 



If we consider Lacerta alone, Ravn's term seems certainly, as a rule, 

 the more applicable of the two ; for on the left side, as well as on the 

 right, there is a ventral ligament, which, however, jiasses from the 

 lung not to the liver but to the ventral body-wall. Ravn, however, 

 mentions that in one specimen he traced a connexion between the 

 lung and liver by means of this ligament ; and, as he says, the usual 

 condition in Lacerta is probably due to the tardier development of 

 the left liver-lobe in the embryo. In the adult of many lizards (e. g. 

 Sphenodon, Trachydosaurus, Uromastyx) the ligament on the left side 

 is either not at all or but slightly developed and does not extend as 

 far back as the anterior margin of the left liver-lobe. And on the 

 other hand, in Amphisbcena, where the left ligament is well developed, 

 it connects the lung and liver. 



I think that the more definite term which I have employed is justi- 

 fied, especially when we consider the homologous but moresymmetrical 

 parts in birds, where it is the liver-lobes and not the lungs that are 

 kept in place by these ligaments ; moreover, the corresponding term 

 pulmohepatic recesses serves well to describe those portions of the 

 peritoneal cavity which are enclosed laterally by these ligaments. 



The membranes which I have called oblique ligaments of the liver, 

 Ravn calls the ligamentum suspensorium hepatis accessorium (dextrum 

 and sinistrum respectively). Ravn's term has the advantage of 

 greater definiteness, but it is long. I may repeat that the develop- 

 ment of these hgaments in different types of Lizard varies both as to 

 size and number, for there may be more than one on a side. This 

 seems to indicate that they liave only a general morphological value. 

 They are either (as llavn calls them) accessory suspensory ligaments, 

 or (as I have said above) ligaments complementary to the pulmohepatic 

 attachments of the liver, in those forms where the latter are not, 

 as they are in the bird, calculated to give sufficient support to that 

 organ ventro-laterally. 



NoTember 23, 1889. G. W. B. 



VIII. EXPLANATION OF PLATES XLVI.-XLIX. 



a.al, right allantoic arterj'. 

 a.al', left allantoic artery. 

 al, alimentary canal. 

 als, allantois. 

 ao, dorsal aorta. 

 ap.23, pulmonary aponeurosis. 

 b.g, gall-bladder, 

 c, heart. 



c', wall of heart. 

 cl, clavicle. 



