Mr. W. Clark on the Animal of Dentalium Tarentinum. 329 



terior, observes that it is the only molluscum that has it so situ- 

 ated ; but this anomaly, if it be so, I think I have disposed of. 



Those organs which I consider to be the symmetrical branchiae 

 are termed by M. Deshayes the lobes of the liver, each pouring 

 into the stomach the bile by their biliary vessels. I cannot per- 

 suade myself that this view is correct ; I have submitted them to 

 the microscope, and in each principal strand I have seen the 

 leading vein distended with red blood as well as in the net-like 

 connecting ramifications ; I therefore consider what are called 

 the biliary vessels to be the branchial veins conveying the blood 

 to the heart instead of bile into the base of the stomach. M. Des- 

 hayes in his figure has omitted to mark the vein which runs at 

 the dichotomous points of his organ, which, when viewed under 

 high powers, is very visible, and which I take to be the branchial 

 vein. 



What I term the salivary glands, are the branchiae with M. 

 Deshayes, combining the functions of tentacular he does not 

 mention such glands. I must consider this assumption incorrect ; 

 and to support this opinion I state that the heart is separated 

 the whole length of the stomach from the bases of what M. 

 Deshayes terms the branchiae : this is a position without parallel, 

 as that organ is invariably in the closest contact with one end 

 of the branchiae. That naturalist certainly connects the two organs 

 by stating, as I think erroneously, that the heart sends great 

 and numerous vessels to the branchiae. Now the heart never 

 transmits blood directly to the branchiae, but impels it into the 

 system by arteries and veins, from whence, as I have already 

 stated, it reverts to those organs. 



The filaments in dispute I have submitted to microscopical 

 observation ; they only present the appearance of a complicated 

 mass without a trace of particular arterial and branchial vessels, 

 and they have nothing like the symmetry of branchiae ; I believe 

 them to be merely secreting glands, and may perhaps combine 

 tentacular functions. 



M. Deshayes is, I think, in error in stating that the aliment 

 undergoes a second mastication : this idea has arisen from his 

 having divided the gizzard into two parts, one of which he de- 

 scribes as " machoires," and the other as an " appareil dentaire 

 assez compliques j" the fact is, there are no hard parts in the buc- 

 cal pouch, which, when removed, there being no internal oeso- 

 phagus, exposes to view the anterior part of the gizzard, which 

 is likened to two spherical black points gaping like a small 

 bivalve : these are only part and parcel of a whole — the gizzard, 

 which may almost be called the stomach itself, as it fills the en- 

 tire stomachal membrane, with the exception of the convoluted 

 intestine at its base, consequently the aliment has no other mas- 

 tication but of one denticular apparatus. 



