1906.] ANATOMY OF THE OPHIDIA. 25 



dorsal extremities these vessels are pixt into communication with 

 each other by a continuous longitudinal vessel which is an extension 

 forwards of the first dorsal parieto-hepatic already mentioned. 

 Some, if not all, of the dorsal pai^ieto-hepatic veins (which vary 

 considerably in calibre) are joined by branches from the stomach. 

 In addition to these special branches reach the stomach from the 

 parietal longitudinal trunk. Although the parietal longitudinal 

 trunk which collects blood from the parietes and transmits it to 

 the liver runs on the left side only and has no fellow on the right 

 side, it receives intercostal twigs from the right side. It is to be 

 noted that the continuous longitudinal trunk lying on the parietes 

 is characteristic of the Boida3 in general, though I am not able at 

 present to assert that it difierentiates them from other snakes. 



Note zipon certain Stn(,ctural Differences hetiveen the Species 

 of Anaconda, Eunectes murinus and Eunectes notseus. 



Hitherto the species Eunectes notceus, the Southern Anaconda, 

 has been distinguished from its ally the more common form by 

 its lighter colour and by the markings generally, into which I 

 have no occasion to enter, as they have been dealt w^ith by its 

 describer, the late Prof. Cope*. 



I have found in dissecting examples of the two species that there 

 are certain differences in the viscera which seem to distinguish also 

 the two species from each other. Upon one of these difi"erences 

 I lay more stress than upon the other, because I have been able 

 to verify it in two examples of Eunectes murinus and three 

 examples of Eunectes Qiotceus, including among the three the two 

 young specimens which form the subject of the present communi- 

 cation. This difierence concerns the pancreas and spleen. In 

 Etmectes notceus the pancreas is a large bilobed gland which lies 

 in close contact with the duodenum and remote from the spleen, 

 which is on a level with the front end of the gall-bladder. 



In two specimens of Eunectes murinus I find the following 

 arrangement of these two viscera: — In both the pancreas is 

 divided into two parts, of which one is situated, as is the whole 

 pancreas in E. notceus, close to the intestine. There is also another 

 piece of pancreas lying in front of and in contact with the spleen, 

 which itself has much the same position that it has in E. notceus. 

 The duct from the anterior part of the pancreas runs to and 

 buries itself in that piece of the pancreas which lies in juxta- 

 position to the gut. In addition to this difierence, I find in both 

 specimens of E. murimis one or two splenculi in the neighbourhood 

 of the spleen and anterior portion of the pancreas. I presume 

 these to be splenculi on account of their colour and general 

 appearance. A dissociation therefore of the pancreas into discrete 

 portions is accompanied by that of the spleen. Upon this 

 anatomical difierence I lay some stress, inasmuch as it is to be 

 found in more than one example of each species. 



* P. Acad. Nat. Sci. Philad. 1862, p. 70. 



