ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 793 



tion, which lies in the spheres, may be very variously coloured. The 

 author details the influence of various chemical reagents, and con- 

 cludes with a short account of the so-called calcareous cells. 



Renal Organ of Prosobranchiata.* — Dr. B. Haller describes in 

 detail the renal organs of FissureUa, Haliotis, Turbo rugosus, Dolium 

 galea, Cassidaria ecMnophora, and Murex trunculus. 



In comparing the organ in various branchiate gastropods he first 

 directs attention to the arrangements seen in the Placophora, which 

 were almost simultaneously described by Mr. Sedgwick and himself. He 

 has now been able to recognize the error of his own and the exact- 

 ness of the other anatomist's description of the opening of the renal 

 infundibula into the pericardium ; a point as to which Mr. Sedgwick 

 has been supported by Van Bemmelen. 



It is clear that the elongated form of the kidney of the Chitons 

 represents a primitive arrangement, and that that of FissureUa is 

 derived from it, the renal acini becoming more and more concentrated 

 as the whole organ becomes shorter and wider. Haliotis stands near 

 to FissureUa, but with regard to histological details it approaches 

 the Trochidae, for there are two kinds of renal epithelia, while the 

 Chitons and FissureUa have but one ; there is, in other words, a 

 division of labour in the kidneys of the more advanced forms. 



It would seem that, the higher the group, the greater the need for 

 a larger reservoir for the excretions ; at any rate in the Trochidfe 

 the reservoir is very large as compared with that of the Haliotidae. 

 In the consideration of this question, we must not neglect the in- 

 fluence of the torsion of the body, which results in an increased 

 pressure on the renal organs ; this is very marked in the Doliidae ; 

 in that group the hinder lobe of the organ is broken up into three 

 connected parts which lie more [Cassidaria) or less (Dolium) close to 

 one another, or form, as in the Muricid^e, a comj)act mass. These 

 lobes are histologically different from the anterior. 



In comparing the renal organ of these molluscs with those of the 

 Opisthobrauchiata, and especially the Nudibranchs, our study must 

 begin with Bomella and the Dorididfe, for these have retained the 

 primitive form, while the sac of Phyllirhoii is undoubtedly secondary. 

 Bomella lias a very acinous kidney, not unlike tliat of Chitons, and 

 indeed it has a closer resemblance than have the kidneys of tho 

 higher Prosobranchs. 



Nervous System of Buccinidse and Purpuridae.f — M. E. L. 



Bouvior states that tho Buccinidaa and Purpurida) are, to use tho 

 language of v. Ihcring, chiastoneurous save that the subintcstinal 

 ganglion is connected with the commissural ganglion by an accessory 

 connective ; this is very short in Purpura, still sliorter in Buccinum, 

 and replaced by a close union in Concholepas ; thus in tlie proboscidial 

 region there is a group of centres whicli form throe ousophageal 

 collars, and have in common tlio two cerebral ganglia which are 

 situated above the ojsophagus. The relations of these centres to the 



* Mori-hol. Jahrb., xi. f ISH.'j) pp. If):', (4 plw.). 

 t Comptcs ReuduB, c. (ISHf)) pp. 1509-12. 



