202 Dr. Maton's and Mr. Rackett's 
MOLINA, 
io his Natural History of Chili, includes the Testacea of that coun- 
try, which he has described in a scientific manner. 
The reproduction of the head of the common Snail, a subject 
to which the attention of physiologists had been first directed by 
Bonnet, occupied at this time the notice of one of the most saga- 
cious observers of the age, the justly celebrated 
SPALLANZANI, 
whose experiments and observations may be found amply de- 
tailed in the Mem. della Soc. Ital. for the years 1782 and 1784. 
This valuable paper contains a variety of very curious facts ; and 
the first part of it is illustrated by nine figures, which exhibit va- 
rious states of the decapitated animal. 
In recording the description given by 
GIOENI 
of. a new genus found on the shores of Catania, we have, unfor- 
tunately, only to commemorate a very remarkable mistake made 
by that naturalist, the supposed new genus having been disco- 
vered to be merely the gizzard of Bulla lignaria, so well described 
by our countryman, Mr. George Humphreys, in the 2d volume 
of the Linnean Transactions. This detection of the mistake, how- 
ever, was not made until seventeen years after the publication 
of Gioeni's book. So little suspicion was entertained of the 
substance thus brought to notice not being a real shell, that it 
obtained a scientific name as such (Triola Gioenii) from Professor 
Retzius, and occupied a place in the system of the late M. Bru- 
guiere, under the appellation of Gioenia Sicula. For the ascertain- 
ing of its real nature we are indebted to M. DRAPARNAUD, 
whose account may be found in the Nouv. Journ. de Physique. 
LIGHT- 
