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Show 105 ON THE VISCER4L ANATOMY OF THE LACERTILIA. [Feb. 7, 2. Bile-ducts. The accompanying drawing (fig. 4, p. 105) illustrates the very remarkable condition of the bile-ducts which characterizes Varanus salvator; the bile-ducts, both cystic and hepatic, form a highly complicated network, which is found in many serpents, but not, so far as I am aware, in any other Lizard. This fact, however, is not new, but has already been recorded1 by Pagenstecher, who, however, has not stated what particular species his observations referred to. I have therefore thought it worth while again to brim.; this matter forward, as 1 am able to state the exact species in which this structural peculiarity occurs. It is important to notice that it is only in Varanus salvator that the cystic and hepatic ducts form a network ; in the other species of Varanus and Monitor which I have had the opportunity of dissecting the bile-ducts are quite single, as in other Lacertilia: I find that Dr. Giinther, who has dissected Regenia ocellata2, R. albigularis, and Monitor niloticus3, makes no mention of any resemblance to Varanus salvator; I conclude therefore that in the former species also the bile-ducts are single. In Alligator lucius (Bronn's ' Thierreichs,' Taf. C. fig. 4) there appears to be just a trace of this network of bile-ducts. In the same work Hoffmann refers to the similarity which the teeth of Monitor show to those of the Crocodilia in their development. Mr. Bouhuger has kindly directed m y attention to a note in the ' Zoolo-gischer Anzeiger ' (Bd. x.), by Van Bemmelen, upon the structure of tbe vessels of the neck in the Sauropsida. From his results it would appear that the Monitors differ greatly from other Lacertilia, and are, in fact, more aberrant than even Hatteria. These facts are all in harmony with m y contention that the Monitors should be widely separated from other Lacertilia, and some of them are by no means at variance with my belief that the Monitors show Crocodilian affinities. Summary. The principal facts recorded in the present paper and the conclusions to which they lead are as follows :- (1) The Varanidae differ from other Lacertilia in two important particulars :-in (i.) the occasional complication of the cystic and hepatic ducts, which form a network, (ii.) the presence of a fold of peritoneum, reflected from the lining peritoneum of the abdominal cavity, which surrounds the abdominal viscera. (2) This fold of peritoneum has its exact counterpart in Crocodilia and Aves, where, however, the subdivision of the ccelom into a number of separate cavities is carried on still further. (3) The Varanidae, therefore, alone (?) of existing Lacertilia show the first beginnings of the subdivision of the ccelom, which reaches its extreme in the higher Sauropsida. 1 Wiirzburg Naturwiss. Zeitschr. i. p. 248. ' P. Z. S. 1860, p. 60. i p. Z. S. 1861, p. 109. |
