102 MR. F. E. BEDDARD ON THE VISCERAL [Feb. 7, 



In Cydodus gigas, however, there is a curious difference ; the 

 timhilical hgament is double, two distinct membranes passing between 

 the liver and the ventral parietes ; these unite anteriorly into a single 

 membrane ; the right-hand one probably represents the single 

 umbilical ligament of other Lizards, since it bears the vein. As I 

 found this in two specimens, it may be regarded as characteristic. 



In Plestiodon auratus a fine tendinous line traverses the lower 

 sinface of the Uver, running parallel to the attachment of the 

 umbilical hgament ; this is very probably the rudimentary represent- 

 ative of the second ligament present in Cydodus. These two genera 

 are commonly assigned to the same family (Scincidae). 



In Trachijdosaurus ruffosus, another member of tlie same family, 

 the disposition of the umbilical ligaments is identical with that of 

 Cydodus. 



These points of difference between the Scincidae and Lacertidae, &c., 

 do not seem to me, for reasons wliich will be brought forward 

 presently, so important as the presence or absence of the horizontal 

 septum ; the presence of this separates the Varanidse from all other 

 Lizards which I have been able to examine. It is, in any case, 

 opposed to the association of the Varanidee and Lacertidse into a 

 suborder Fissilinguia. 



I can find no statement about this structural feature, which 

 separates the Varanidse from other Lacertilia, in any text-liooks to 

 which I have had access ; there is nothing, so far as I can ascertain, 

 in the Treatise on the Lacertilia, by Prof. Hoffmann, which occupies 

 part of Volume vi. of Bronn's ' Thierreichs.' Prof. Rolleston, in 



his ' Forms of Animal Life ' ', states that " the lungs in the 



Loricata ( = Chelonia and CrocodiHa) differ from those of other 

 Reptiles in not projecting freely into the general cavity of the body, 

 dissepimental processes of peritoneal membrane separating them 

 from it, and foreshadowing thus, as also by tlieir possession of 

 intrinsic muscular fibres, the diaphragm of warm-blooded animals." 

 Hoffmann, in the work referred to", distinguishes the CrocodiHa 

 from the remaining Saurians, by virtue of the fact that the latter, 

 instead of having the body-cavity divided into numerous compart- 

 ments, as in the CrocodiHa, " possess only two sacs, the pericardium 

 and the peritonaeum ; from tlie latter is derived the covering of the 

 lungs." Both these writers, however, quote a paper by Briicke \ 

 which is chiefly devoted to a statement ot the fact that in Faranus * 

 the mesenteries contain unstriated muscular fibres ; in this paper, 

 however, Briicke remarks that the muscular fibres of the uinbiHcal 

 ligament are continued into a membranous diaphragm (" haiitige 

 Zwergfell "). Whether this diaphragm represents the liorizontal 

 septum which I have described in this paper as existing in Varativs, 

 I am unable to say, as there is no further description of it. Evidently, 

 liowever, Profs. Rolleston and Hoffmann have not interpreted Briicke's 



' Inlrodiutiou. p. Ix. ^ P. 922. 



^ Wk-ner 8ilzuiig8ber. vii. (1852), p. 246. 



* Levdig liHS subsequently sliowa that this holds good in the case of other 

 Lizards. 



