

PARASITIC HABITS OF CRUSTACEA. 239 
was described by M. Lorois in the “Révue et Mag. de Zoolo- 
gie," in 1852, as A. Nouryi. Mr. Conrad, in his monograph 
of the genus, mentions that Capt. O. Swain, of Nantucket, 
in 1850, obtained a number of this species in the same vicin- 
ity. They were observed on the surface of the water on a 
perfectly calm day, when the sun was very hot. They ap- 
peared in large numbers, in one group at first, and then dis- 
persed in smaller groups of twos and threes, moving with 
great rapidity over the surface. Approaching them with great 
caution, a number were secured. A year or two ago Capt. 
Dow, well known as an indefatigable collector, sent to the 
Smithsonian Institution two fine specimens captured in Lat. 
10° south, Long. 90° west, almost the same spot whence they 
were originally obtained by M. Noury. So far as I am able 
to ascertain they have not been elsewhere detected. In one 
of them the ova, of a red color and very small, were agglu- 
tinated to the outside of the spire, as previously noted. 
It is pleasant to add that our first detailed account of the 
Argonaut and its development, was published by a lady; 
Madame Power, who made her observations in the Mediter- 
Tanean, having a sort of marine enclosure made, where she 
Kept these animals and observed their habits from life. 

ON THE PARASITIC HABITS OF CRUSTACEA. 
BY A. E. VERRILL. 

Taere are few subjects pertaining to the study of animals 
more eurious and interesting than the various phenomena 
Connected with the parasitism of certain species upon others. 
This subject is also one that has many important practical 
bearings, since our worst crop-destroying insects are kept in 
check mainly by insect parasites, feeding either on the eggs, 
ug larvee, or the mature insect. Our domestic animals also. 


