30 Moll 
MOLLUSCA. 
or a larger number of smaller ones, only distinguished by their greater 
length from the rest of the epithelium. During the formation of a tooth 
the odontoblasts are not replaced by new ones from behind, but the same 
group develops all the teeth of the same longitudinal series. The 
arrangement of the groups of odontoblasts varies with that of the teeth 
in a transverse row of the radula. The basal membrane, which is dis¬ 
tinctly laminated, is formed by the ends of the matrix-cells splitting into 
longitudinal fibres, which are placed side by side. The teeth become 
stronger by a secretion from the cells situated above the radula. 
Yon Jeering (201) proposes the names “ Basalplatte,” “ Epithema,” 
and “Dentikel ” for the base of attachment, reflection, and cutting-points 
of the teeth of the Gastropod radula ; also, to write the number of 
denticles in each tooth below the number of teeth in the formula ; and, 
further, to indicate the three parts by different colours in drawings. 
Jousseaume (206) upholds the opinion that the radula is only to be 
used for classificatory purposes with caution, and in connection with the 
other organs of the body. 
Schacko (321) describes the buccal armature of five Uelicidce. 
4. Circulatory System . 
Remarks on blood of Helix pomatia , H. aspersa , Limnceus stagnalis, 
Paludina vivipara , Anodonta cygnea ; MacMunn (244). The same author 
gives particulars regarding the existence of myohsematin and histo- 
hsematin in certain Mollusks, with an account of their spectra (243). 
The influence of electric currents and poisons upon the hearts of 
Octopus, Pterotrachea, Aplysia , and Helix has been investigated by Ran¬ 
som (305). 
The inception of water by Lamellibranchs is exhaustively treated by 
Fleischmann (129). Muscles pass both from the right and left sides of 
the body towards the margin of the shell, and these eventually unite, and 
form a complicated interlacing with each other, and for this covering of 
the viscera the name “ Muskelhaube ” (muscle-hood) is proposed. When 
the foot of Anoclon or Gyclas is extended, waves are seen passing along it 
from behind forwards as though of fluid passing through a hollow elastic- 
walled body. Earlier observers had seen that when a muscle is removed 
from the water, jets of this are seen to issue from what, under a lens, 
appear to be apertures in it. The author has made serial sections of 
animals carefully killed in picro-sulphuric acid and corrosive sublimate, 
and finds no such pores. 
Griesbach probably was deceived by the single layer of epithelium, 
which in some places forms the only boundary between the exterior and 
the “ pedal artery,” having been broken through, a result to which his 
modes of pieservation were not unlikely to lead. The author took Ano- 
dons, and while the foot was extended pressed the valves together so that 
it could not retract, and then killed the animal by immersion in hot cor¬ 
rosive sublimate solution. By this means the pori should be preserved, 
but none were found. As regards injections, the author points out the 
illegality of many of the methods of Griesbach, and especially of the 
