ANATOMY AND PHYSIOLOGY. 
Moll'll 
Notes on the development of the Cephalopods by M. Ussow, Arch. 
Biol. ii. pp. 553-635. Abstract in J. R. Micr. Soc. (2) ii. pp. 328-330. 
Development of Bithynia teniaculata (L.), described by P. T. Sara- 
sin, Arb. Inst. Wiirzb. vi. pp. 1-68, 1 pi. 
A few observations on segmentation in the Nudibranchiata , and the 
existence of a velar groove in them, resembling that of the Pteropods and 
Heteropods, the first stages of development in Janthina , and the origin 
of the nervous system by proliferation from paired thickenings of the 
opiblast in Purpura lapillus and Mur ex erinaceus, by A. C. H addon, 
Q. J. Micr. Sci. (2) xxii. pp. 3G7-370, pi. xxxi. 
A. Kowalewsky makes some observations on the first stages of 
development in Chiton polii (Phil.), describing the formation of the 
intestine, the pedal gland, the nervous system and the shell, which makes 
its first appearance in the form of seven groups of highly coloured cells. 
Zool. Anz. 1882, pp. 307-310. 
The first stages of development in the European Oyster are described 
by R. Horst, Q. J. Micr. Sci. (2) xxii. pp. 341-346, pi. xxvii. According 
to him, the sliell-gland is flattened out, and passes iuto a saddle-shaped 
thickening of the epiblast, giving origin by its secretion to a thin cuti- 
cular membrane, the future shell. The bivalve shell is therefore at the 
beginning an unpaired formation, not developed from two separated 
valves, and afterwards united by the hinge. Also in Zool. Anz. 1882, 
pp. 1 GO-1 62. 
Notes on some of the early stages of development of My a arenaria 
(L.), segmentation of the egg the same as in Ostrea and A nodonta ; 
J. A. Ryder in Ferguson’s Report on the Fisheries in Maryland, 1881, 
appendix 4, and Am. Nat. xvi. p. 911. 
9 . The Shell generally. 
T. Tullberg (Sv. Ak. Handl. xix. No. 3) in an elaborate and very 
well illustrated treatise on the structure and growth of the shells of 
Mytilus edulis, Modiola modiolus , Margaritana margaritifera , Ostrea 
edulis , and Buccinum undatum , comes to the conclusion that the shell is 
for the greater part a separate product of the cells of the mantle, the 
formation of the substance being best compared with the same process 
in Homarus vulgaris , as in them also the outer parts of the cells are 
gradually changed into a shelly substance. 
Folin states, from experiments made by means of the air-pump, 
that the whole shell of several land-snails, for iustanco Cyclostoma 
elegans, is permeable by air ; in others only distinct parts (for instance, 
the umbilical region) are permeable ; in some Cyclostom.atidce the opercu- 
lum ( Aulopoma ) or peculiar sutural tubes seem to admit air into the 
interior of the shell ; the truncation of Rumina decollata , and of many 
Cyclostoma, tides may also serve for the same purpose. Act. Soc. L. Bord. 
xxxiv. [I860]. Abstract in J. de Conch, xxx. p. 65. 
A. Hyatt, in “ Transformations of Planorbis at Steinheim, with 
Remarks on the effects of Gravity upon the forms of Shells and Animals,” 
suggests that the influence of gravity, combined with heredity, must be 
1882. [vol. xix.] c 2 
