ZOOLOGY. 777 



Hancock. Occasionally, as in tlie Argiope neopolitana, there are two 

 hearts. On the other hand, in some forms, as Crania anomala, there is 

 " no heart," but " numerous enlargements on the 'vein.'" The so-called 

 " afferent brachial canal" of Ilaucock is now affirmed to be "really the 

 supra- cesophogeal nerve," and "further, the plexus which Hancock de- 

 scribes as circulatory, are really branching and anastomosing connec- 

 tive tissue-cells." In one of the examined Brachiopods ( Crania anomala) 

 the supra-oesophageal ganglion is replaced by a " narrow fibrillar com- 

 missure." A "brachial vessel, sending off vessels to the cirrhi, runs 

 along the whole length of the brachial sinus behind the ojsophagus, 

 communicating by paired branches with the oesophageal blood-sinus, 

 and so with the heart." {Zool. Anzeiger, v. 8. pp. 164-1G7 ; J. R. M. K 

 (L»), V. 5, p. 440.) 



MOLLUSKS. 



Acephals. 



Action of the foot in bivalve mollusls. — The movements of the foot in 

 Lamellibrauchs, or the bivalve mollusks, have been studied by Dr. A. 

 Fleischmann. It is maintained that the so-called aquiferous i^ores in 

 the foot are " neither the orifices of glands nor artefacts. This being so, 

 the3' cannot serve as a means of communication between the blood vas- 

 cular system and the surrounding water. Such streams of water as are 

 seen on contraction are not normal vital phenomena, but are patho- 

 logical. Even if there were pores, they could not, for mechanical rea- 

 sons, have the functions that have been ascribed to them. The swelling 

 of the foot is due to the entrance of a certain quantity of blood, which, 

 during repose, is stored up in the pallial reservoirs ; the blood is aided 

 by the closure of a strong valve and by the simultaneous relaxation of 

 tlie musculature of the foot, the lacunse of which become filled by blood. 

 When the foot undergoes erection there is no change of volume of the 

 whole animal, but only a change in the volume of separate parts, due 

 to the dislocation of the blood. It has not been proved that water is 

 taken up by the kidneys or intercellular ducts. The Lamellibrauchs 

 do not need to take in water. What is true of them is also true of other 

 groups of mollusks." {Zeitschr. Wiss. Zool., v. 41, pp. 367-431 ; J. B. M. 

 S., V. 6, p. 52.) 



Byssogenous glands and Aquiferous pores in Lamellibranchs. — Thebys- 

 sogenous glands and pores of bivalve mollusks, as well as the so-called 

 aquiferous pores of the foot, have been studied by Prof. T. Barrois. 



"In the present state of knowledge," he indicates, "it is generally 

 admitted that the byssus is the secretion of special glands," but the ex- 

 tent to which such glands are developed had not been known until the 

 ])rofessor was able to demonstrate that Lamellibranchs generally ex- 

 hibit more or less well marked traces of this byssogenous apparatus. 



