122 PROF. G. B. HOWES ON THE AZYGOS [Feb. 21, 



In June last Major Cassel presented to the Society two Trap-door 

 Spiders from Natal. These are still living, but up to Saturday last 

 I had not seen either of them out of their cells ; on that day I, after 

 some trouble, got one out, and, as well as I was able, made a sketch 

 of it. 



I wrote to the Rev. O. P. Cambridge respecting these Spiders, 

 asking him if he could tell me anything about them ; he replied, 

 saying, that he "confidently expected the S.- African Trap-door 

 Spiders would be new to science, as he did not, at that moment, re- 

 member anything of the kind of the size I mentioned." 



These Spiders have fed principally upon Cockroaches, and the one 

 I had out on Saturday was in splendid condition. 



The following papers were read : — 



1. Note on the Azygos Veins in the Anurous Amphibia. 

 By G. B. HowEs^ F.Z.S., F.L.S., Assistant Professor of 

 Zoology, Normal Sch. of Science and B. Sch. of Mines. 



[Received February 7, 1888.] 



It is customary to regard the presence of the vena cava inferior 

 as a special characteristic of the air-breathing Vertebrata, and the 

 view most generally accepted and taught holds this vessel to be a 

 late development, which replaces the posterior-cardinal veins of fishes. 

 Indeed, some authorities would regard its presence and absence as 

 distinctive of the air-breathing and water-breathing series respec- 

 tively. Balfour wrote of it^: — "The venous system of Amphibia 

 and Amniota always differs from that of fishes in the presence of a 

 new vessel, the vena cava inferior, which replaces the posterior car- 

 dinal veins, the latter only being present, in their piscine form, 

 during embryonic life." 



Chief amongst recent researches into the morphology and develop- 

 ment of the venous system are those of Parker"^, Hochstetter*^ 

 Meyer". The work of the second-uamed author will become little 

 short of revolutionary, should his deductions hold good. He claims, 

 as the chief result of his investigations, to have shown that the vena 

 cava inferior, instead of being throughout its whole extent a primarily 

 independent vessel, is a compound structure — the product of a fusion 



^ Comp. Embryology, vol. ii. p. 538. 



^ " On tlie Venous System of the Skate," Trans. New-Zealand Instit. vol. xi. 

 1880, p. 49. 



' " On the Blood-vessels of Mustclus antaroticus" Phil. Trans, vol. 177. 1886, 

 p. 685. 



* " Beitr. zur vergleichend. Anat. und Entwicklungsgesch. d. Venensyst. der 

 Amphib. und Fische," Morpbolog. Jabrb. vol. xiii. 1887, p. 119. 



5 •' Ueb. die Bildung d. hinteren Hohlvene b. d. Siiugethieren," Anat. Anzeiger, 

 vol. ii. 1887, p. 517. 



' " Ueb. d. EntwiokluDg des Herzens und d. gro.ssen Gefassstamme b. d. Sela 

 chiern," Naples Mittheilungen, vol. vii. 1887, p. 338. 



