1906.] VASCULAR SYSTEM OF THE CROCODILIA. 625 



in question before they finally join to enter the liver. An inspection 

 of the figure will do away with the necessity of a detailed description. 

 In addition to these three stouter vessels a more slender trunk 

 arises (behind them) and is connected above with the veins 

 running directly from the stomach to the liver. This vessel (in 

 both specimens, I believe, but certainly in one) is also derived 

 from the lateral parietes, and thus exactly corresponds to a similar 

 vessel in Crocodilus catcqohr actus, which is also in the same way 

 the last of the series. 



In Caiman sclerops there are again difierences of detail. The 

 right and left sides are shown in the accompanying figures (text- 

 fig. 106, p. 623). In both cases there is a branch from the lateral 

 parietes, which, as in other Crocodilia, is the last of the sei'ies of 

 the parieto-hepatic veins. On the right side only two trunks arise 

 from the azygos, but the posterior immediately divides to shortly 

 reunite with both of the primary branches. On the left side 

 there are only two vessels arising from the corresponding azygos. 

 These are fused immediately after their origin, but divide again 

 at once. Further details will be obvious from an inspection of 

 the illustrations. In comparing the course of these vessels in the 

 several Ci'ocodilia which I have had the opportunity of examining, 

 it is possible to arrive at certain differences and agreements 

 between the four species dealt with. 



In the Crocodiles [C. acutus'* and C. cataphractus) the number 

 of trunks forming the dor-sal parieto-hepatic aflluent of the portal 

 system is greater by one or two than in either Osteolcemus or 

 Caiman. On the other hand, in the two last-named genera the 

 interconnections between the several trunks before they unite to 

 open into the liver are to be remarked, and are not seen in the two 

 species of Crocodilus. Furthermore — but as this depends upon 

 negative evidence, less stress is laid upon it — the vein in question 

 in Osteolcemus and Caiman is connected before its entrance into 

 the liver with the stomach plexus of veins. It is interesting to 

 observe that in this system of veins as well as in others 

 Osteolcemus and Caiman show likenesses to each other and 

 corresponding differences from Crocodilus. 



In addition to the constantly present laterally arising trunk 

 which in all the Crocodilia examined joins the dorsal parieto- 

 hepatic vein, there are other vessels also lateral in origin which 

 have a separate entry into the liver. In Osteolcemtcs tetraspis 

 three slender veins arise from the parietes laterally more ventrally 

 than the lateral aflluent of the dorsal parieto-hepatic already 

 described ; each enters the liver separately. On the left side I 

 could find only one corresponding vein. In Crocodilus cataphractits 

 each lobe of the liver has also a corresponding vein originating 

 from the lateral parietes. It enters the liver between the 

 anterior abdominal and the dorsal parieto-hepatic veins, I have 

 not observed this vein in other Crocodiles, 



* P. Z. S. 1905, vol. ii. p. 466. 



42* 



