96 MR. GARNER ON THE ANATOMY OF THE 
Having shown the fatal effect which would be produced by the concentration of the 
sea water on the branchie of its bivalve inhabitants, it is worth inquiry, how in those 
animals which, on the retreat of the tide, are exposed to the desiccative action of the 
sun and air, the evaporation of the water is prevented. Those animals which possess 
naked ciliated branchie have the power of retracting them into sheaths, when they, like 
many species of Doris, frequent the bare rocks ; or if this power of withdrawing them 
does not exist, as in other species of Doris, the Tritonia, Eolida, &c., they take care to 
cover themselves with the wet Alg@, or to lurk in shady crevices. The Patella in hot 
days sticks firmly to the rocks, so as to prevent the escape of the confined moisture. 
The Ascidie frequent pools among the rocks which are not drained at low water. The 
Actinie, Lobularie, &c. adhere to the dripping under surface of the cliffs, or frequent 
shady places. The Polypifera either reside in deep water, or find a habitat where the 
sun does not reach them. Those Lamellibranchiata which, like the common Muscle, 
are exposed on the bare rocks to the action of the sun and air, have the valves fitting 
to each other most exactly, preventing all evaporation. When the valves are open at 
any part, the animal either inhabits deep water, as many species of Pecten, or has the 
power of burrowing in the mud or sand, when left dry by the ebb of the tide. The 
Gasteropoda also hide themselves from the sun, though their branchie are not much 
exposed. Aristotle says they hide themselves during the dog-days. Along the sandy 
beach we see numerous holes leading to the branchie of different animals, which by 
boring hide themselves, and protect their organs from the effect of evaporation, as well 
as obtain a supply of water loaded with nutrient particles. 
The phenomenon of animal phosphorescence seems almost peculiar to ciliated ani- 
mals. In an Annelide, which presents the phenomenon very beautifully, covering in 
profusion the nets of the fishermen when drawn up, I found that the luminosity 
stopped when the action of the cilia was destroyed; that it was greatest when they 
were most active ; and that the tremulousness of the light appeared to correspond with 
an unsteadiness of the vibration. It appears worth inquiry, whether the appearance 
does not arise from the friction of the cilia upon the particles of water. The experi- 
ments of Beccaria seem to prove that the light is not owing to any chemical principle, 
and that it exists in exactly such circumstances as the cilia would continue to vibrate 
under. 
Reproductive System. 
The opinions of Leuwenhoek, Mery, Prevost, and Dumas, &c. on this point respect- 
ing the different sexes of the Lamellibranchiata are well known ; but there appears every 
reason to believe that there is no difference in the individuals as to sex, and that the 
ova are discharged from the ovaries in a state fit to develop; or, in other words, that 
they are fecundated before they leave the ovaries by testes which are conjoined with 
those organs. Some authors have mistaken the excretory organs for testes. The ovaries 
differ much in their situation ; sometimes they form distin¢t parts, sometimes they are 
