ZOOLOGY AND BOTANY, MICEOSCOPY, ETC. 719 



pericardium by a very wide canal, whicli passes between the left renal 

 tube and the dorsal wall of the pallial cavity ; the epithelium of this 

 canal has very long and powerful cilia, which are turned towards the 

 kidney. As in Cyclostoma, there may be one or more rows of cells on 

 the transverse lamellae which project into the renal cavity. In the 

 kidney of Valuata there is only one kind of cell; these are ciliated, and 

 contain a number of very small yellowish granules. When they are 

 about to fall away their protoplasm contains fine vacuoles. Their debris 

 form a kind of mucus in the middle of the renal cavity, and in this their 

 nuclei, only slightly modified, may be made out in sections. Some 

 points raised by M. Eemy Perrier with regard to the physiology of 

 secretion are criticized. 



The pericardiac epithelium is not glandular, but in the wall of the 

 auricle there are racemose masses of cells with homogeneous contents, 

 which absorb powerfully colouring reagents ; these cells correspond 

 almost exactly to those described by M. Sabatier in the heart of Mytilus, 

 and that author is probably right in regarding them as having a secreting 

 function. 



M. Garnault's observations on the nervous system correspond pretty 

 closely to those of M. Bouvier ; neuro-epithelial cells on the part of the 

 mantle between the gill and the body-wall appear to represent an ill- 

 defined organ of Spengel. Neither the structure nor the innervation of 

 the pallial filament justify us in regarding it as a gill or false gill ; 

 Moquin-Tandon was j)robably right in considering it to be the homo- 

 logue of the pallial filaments of young Paludinse. 



M. F. Bernard has also written * on the anatomy of Valvata 

 piscAnalls. The epithelial cells of the auricle described by M. Garnault 

 are always met with in the Diotocardia, and are identical with those 

 which Grobben has described in the Acephala. There are no arterial 

 capillaries. The abdominal sinuses are prolonged anteriorly by several 

 systems; there is an anterior abdominal sinus which ends near the 

 cardia and arises from the general cavity of the body ; in the mantle 

 there is a large sinus between the rectum and the genital ducts, and 

 there is a system of sinuses which ends in the formation of a transverse 

 pallial vein. The whole surface of the mantle is covered by a network 

 with distinct meshes, which connects the transverse vein, the afferent 

 and efferent branchial veins, the circumrectal lacuna, and a circumpallial 

 sinus which is given off from the anterior abdominal sinus near the 

 pericardium. At first sight this plexus appears to be formed of true 

 capillaries, but it really only consists of lacunae. 



The gill receives its blood by a large afferent sinus, which is 

 enlarged at the point of attachment of the organ. It differs from that 

 of all the Diotocardia by not being prolonged behind the line of inser- 

 tion into the mantle. The branchial nerve is very large, and gives off 

 to the epithelium delicate fibres, as in Fissurella, and not large bundles 

 as in Haliotis and the Trochidae. 



As to the kidney, the author agrees with M. E. Perrier (see supra). 

 The visceral commissure arises partly from the so-called supra-intestinal 

 ganglion and partly from the large right pallial nerve. The visceral 

 ganglion is to the right and at the bottom of the pallial cavity, on the 

 oesophagus, and at the end of the right salivary gland. There are two 



' Comptea Eendus, cvii. (1888) pp. 191-4. 



