ANATOMY AND PHYSIOLOGY. 
Moll 33 
JIaliotis , and certain Trochidce and Muriciclce , and comes to the conclusion 
that the first is derived from Chiton , in regard to which he recognizes the 
accuracy of Sedgwick’s opinion that the renal infundibula open into the 
pericardium. The arrangement in Hciliotis approaches that in Fissurella , 
but in some respects resembles the Trochidce. Comparisons with the 
Opisthohranchiata are also given. Bornella has an acinous kidney; the 
sac of Phylliroe is a secondary modification. 
The renal organ of certain species of Parmacellce has been investigated, 
some errors previously made in its description corrected ; a “ Nieren- 
spritze ” is described as leading from the pericardium into the kidney ; 
also remarks on other organs ; Simroth (339). 
The so-called ‘‘liver 5 ’of Mollusca consists, according to Frenzel (134a), 
of three kinds of cells : (a) granular ; ( b ) club-shaped, secretory cells ; 
(c) so-called calcareous cells. In Lamellibranchs these last are absent, 
and sometimes the second ; in Chiton and Patella the club-cells are want¬ 
ing ; whilst in the Heteropoda, so far as examined, only the granular 
cells are certainly present. Pulmonata and Opisthobranchiata agree in 
the first two kinds being present; in Pteropods the calcareous cells are 
certainly, and the club-shaped probably, absent. Cephalopoda have no 
granular cells, but their club-cells contain either vacuoles or yellowish- 
brown masses enclosing colourless crystals ; the calcareous cells contain 
spheroidal bodies. 
In Cardium edule the byssogenous apparatus consists of five parts : (1) 
a groove on the inferior aspect of the foot; (2) glands on the margins of 
the groove ; (3) a canal which penetrates the foot from the posterior 
end of the groove and opens into a cavity (“ byssal cavity ”) ; (4) this 
cavity possesses lamellar walls, to which the commencement of the byssns 
is attached; (5) glands united into a compact mass, which pour their 
secretions into the byssal cavity. 50 species were examined, showing the 
apparatus more or less completely developed, except Pholas, Solen , 
Lucina , Diploclonta , in which it was entirely absent. The openings of 
these glands are the only pores to be found in the foot. Barrois (13, 14). 
Formation and minute structure of the byssus of Lamellibranchs dis¬ 
cussed by Cattie (70). 
See also Breitenbach (52) ; and Haddon (153). 
7 . Nervous System. 
Yialleton (371) regards the dotted substance of the Cephalopod 
nerve-centres as corresponding with the neuroglia of Vertebrates ; it arises 
in the embryo as a plexus of fibrils. In the visceral ganglia the same 
continuity of cells and axis-cylinders as in Vertebrates may be observed; 
the differentiation of nervous tissue is more completely carried out in the 
Vertebrates than in the Cephalopoda. The same author (369) finds that 
the nerves supplying the lobes of the buccal membrane in Cephalopoda are 
similar in origin to those supplying the arms, and hence considers that 
the former are to be regarded as small arms with a well-developed 
interbrachial membrane. 
