Miscellaneous. 159 



circulation diflfers greatly in its dej,ix'e of intensity from the branchial 

 circulation of the other Lumellibranchiate Mollusca; it is verj- feeble 

 or almost none ; branchial injections, moreover, are rarely successful 

 and always very imperfect. This deficiency of cii'culation depends : — 

 1, on the small calibre of the branchial vessels ; 2, on the weakness 

 of the flow of the blood, which only arrives at the branchiae after 

 having traversed the Bojanian and other capillary networks ; and, 

 3, on the existence of easy return passages, which allow the blood 

 to return to the heart without having traversed the branchiae. 



The mantle plays an important part as an organ of respiration. 

 But during the period of reproduction it is gorged with eggs or 

 spermatozoids, since it contains the reproductive organs ; it acquires 

 a great thickness and becomes a verj' active visceral organ in which 

 haematosis does not take place, and in which, on the contrary, the 

 blood becomes charged with carbonic acid in consequence of the 

 acti%"ity of the phenomena of nutrition. The respirator^' functions 

 are then performed by the pZfaVec? organs, which are arranged in a 

 close series on the inner surface and near the adherent margin of 

 the mantle. They have been mistaken for simple vessels ; but they 

 are hollow laminae, very regularly sinuous, and with very elegant 

 foldings. Their cavity is rendered spongy by a true reticulum of 

 very delicate elastic fibres. Their surface is clothed with vertical 

 series of cells with long vibratile cilia, which effect the renewal of 

 the water ; the interspaces of these series of cells are occupied by 

 cells with short cUia. These plaited organs receive the blood which 

 returns from the mantle. I regard them as a respiratory organ, a 

 supplementary branchia, destined to play an important part during 

 the period of reproduction, when the mantle does not respire. This 

 opinion is, moreover, in harmony with the fact that the plaited organs 

 are much more prominent and much better filled with blood at the 

 time when the mantle is occupied by the reproductive elements. 

 These plaited organs are therefore neither a part of the corjnis 

 Bojani, as Siebold believed, nor simple vessels detached from the 

 mantle, as has also been supposed. — Coraiites Eendus, August 31, 

 1874, vol. Ixxix. pp. 581-584. 



Note on Herpeton tentaculatum. 



M. Albert Morice, surgeon in the French navy, has kindly com- 

 municated to me that he has succeeded in bringing a living ex- 

 ample of this snake to the Zoological Garden in Paris. He ob- 

 served it in the south-eastern provinces of Camboja ; and writes 

 as follows : — 



^^ Herpeton tentaculatum is ovo- viviparous, bringing forth six young 

 ones at a birth, which are 0-2S m. long. Its food is mixed ; it feeds 

 on tadpoles and small fish, and also on an aquatic plant called by 

 the natives ' Kan giua,' or Jussicea repens of botanists." 



A. GCNTUEK. 



