860 THE AMERICAN NATURALIST. (VoL. XXXV. 
the animals shows a corresponding change ; young lobsters swim with 
great irregularity until the otocyst is developed, after which they 
regularly assume the upright position. It is also interesting to 
observe that immature lobsters newly molted and not allowed to 
form a new otolith reassume the rolling movements of their earlier 
stages and continue in these until opportunity is given them to form 
new otoliths. Thus the results obtained by Prentiss confirm com- 
pletely the view first advanced by Delage, namely, that the otocyst 
has as its chief function that of originating orientation reflexes. 
That it is not an organ of hearing cannot with so much certainty be 
maintained, although its importance in this respect has assuredly 
been shown to be very slight. P. 
Recent Work on Anopheles. — In a recent study on the geograph- 
ical distribution of Anopheles in relation to the former distribution 
of ague in England, G. H. F. Nuttall records with L. Cobbett and 
G. Strangeways (Journal of. Hygiene, Vol. I, January, 1901) a series 
of observations of general interest in addition to much that is purely 
medical. He finds that three species, Anopheles maculipennis, A. bifur- 
catus, and A. nigripes, occur in Great Britain in all districts formerly 
malarious, but extend into regions in which no ague is known to 
have been prevalent at any time. To-day Anopheles is most numer- 
ous in low-lying land containing stagnant or slow-flowing water and 
corresponding to the districts where ague was formerly prevalent. As 
the disappearance of this disease does not depend upon the extinc- 
tion of Anopheles, possible causes, therefore, are: (2) a reduction in 
the number of these insects consequent upon drainage of the land; 
(6) a reduction of the population in infected districts by emigration ; 
(c) the use of quinine; or (7) the extinction of another yet unknown 
intermediary host besides man capable of harboring the parasite. 
The coincidence of the geographical distribution of ague and Ano 
pheles is certainly not as precise as claimed by Grassi, and probably 
the numerical distribution will prove of equal importance. The 
presence of Anopheles in non-malarious districts explains the occa- 
sional occurrence of ague if a malarious subject comes in from other 
parts. 
In another paper on the structure and biology of Anopheles, 
Nuttall and Shipley (Journal of Hygiene, Vol. I, January, 1901) 8° 
a full summary of our knowledge, together with personal observe 
tions. Noteworthy is the fact that the larva of Anopheles, as 
that of Dixa, browse upon matter adhering to the surface film, like 
