766 



this specimen is very similar to the preceeding one except in the confor- 

 mation of the anastomosis between the two external jugular veins. This 

 anastomosis consists of two parts. The first is a vein running from the 

 junction of the right lingual and mandibular veins in a slightly anterior 

 direction across to the left lingual vein. The second is another vein 

 starting from the junction of the left lingual and mandibular veins and 

 running forwards into the previous one just to the left of the mid- 

 ventral line. 



The only other example of a similar abnormality, so far as I have 

 been able to find, is that described by Shore (13). In his note he 

 terms the anastomosis an innominate vein and points out that the tern 

 innominate vein in the frog is usually applied to a vein that is not 

 homologous with the vein so named in man and manuals and which he 

 calls from its factors the sub-scapulo-jugular. But although in his 

 specimen the anastomosis did run in somewhat a similar way to that of 

 the innominate in man (except that it was from right to left instead of 

 left to right) the conformation of the anastomoses in the foregoing 

 specimens shows that they cannot be in any way homologised with a 

 true innominate vein and so his term is misleading. There were in the 

 specimens no trace of disease and it is therefore somewhat difficult to 

 account for the loss of the right pre-caval vein. The loss of this vessel 

 necessitated, as Shore suggests, the formation of another means of 

 return to the sinus venosus and it appears that the blood was forced 

 through normal small anastomoses of the tributaries of the external 

 jugulars which in consequence became dilated. 



Addendum. 

 Since the foregoing note was in the printer's hand another similar 

 abnormality of the venous system has been found in a frog undergoing 

 dissection in this college. It is almost identical with that of specimen A 

 for again it is the right Precaval that is absent, the only difference is 

 that the left Lingual and Mandibular veins opened separately instead of 

 flowing together. In other respects the specimen was a normal adult, 

 male Rana tcmporaria. 



Literature. 



1) Bates on, W., Materials for the Study of Variation. 



2) Bergendal, D., Bihang K. Svensk Vet. Akad. Handl. Bd. 14. 1889. 



3) Bland Sutton, Trans. Path. Soc. 1889. 



4) Cat. Ter at, Ser. Coll. Surg. Mus. 1872. 



5) Eigerman, C. H. & Cox, U. 0., Some cases of Saltatory Variation. Amer,. 



Nat. Vol. 85. 1901. 



6) Gaupp, E., Anatomie des Frosqhes. 



7) Gervais, P., Comptes Rendus Tome LIX. 1864. 



