510 General Notes. [ May, 
test the power of bees to return to their nests when carried to a 
distance ; a considerable number returned safely. Ammophila 
jursuta, says Fabre, searches for the larve of Agrotis segetum, 
which are detected under the surface of the ground by some 
apparently unknown sense. The larva is carefully paralyzed in 
every segment before being buried, which leads the author to 
conclude that the Ammophila originally preyed on insects more 
easily paralyzed, and as it gradually attacked larger insects, its in- 
stincts enlarged, and became hereditary——W. F. Kirby finds 
that hybrids between Smerinthus ocllatus and populi usually show 
traces of hermaphroditism, which seems to indicate that herma- 
phroditism is encouraged by hybridity, and that the usual sterility 
of hybrids may be due to this cause. 
ZOOLOGY. 
ANOTHER VORTICELLA WITH TWO CONTRACTILE VESICLES.—In 
the NATURALIST for August, 1884, the writer described a new 
infusorian belonging to the genus Vorticella, under the name 
Vorticella lockwoodu, one of the peculiarities of which was the 
possession of two contractile vesicles, that being the first recorded 
instance of the occurrence of more than a single pulsating vacuole 
in any of the numerous species. Now, however, I desire to state 
that a similar arrangement obtains in the well-known Vorticella 
monilata Tatem, a species originally discovered in English waters, 
and by no means uncommon on the continent of Europe or in 
this country. It therefore seems somewhat surprising that the 
presence of the two vesicles in this widely distributed form should 
have hitherto eluded observation. The species occurs in this 
locality in some profusion, a colony recently taken attached to 
Myriophyllum from my aquarium being formed, by actual count, 
of two-hundred individuals, another of eighty-three, smaller col- 
lections not being rare. With these I have been able to positively 
determine and demonstrate to a friend the presence of two con- 
tractile vesicles which, when the vorticella is in the proper posi- 
tion, are distinctly visible without a change of focus. The fact of 
their presence is of interest since it is a point in the anatomy of 
th inute creat t previously noted.—Dr, Alfred C. Stokes, 
Trenton, N. F. 
CUVIERIAN ORGANS OF THE COTTON-SPINNER.— Professor F. 
Jeffrey Bell gives a technical account of this almost unknown 
British Holothurian, which is of interest as being the only true 
—that is, aspidochirotous (or with shield-shaped tentacles)— 
member of the class which is known to occur in British seas. 
The organ of most’ importance is that which produces the sticky 
_ Secretion from which these animals have obtained their name, and 
which makes them objects of much dread to the Cornish fisher- 
= men. The producing or cuvierian organs are described as form- 
_ ing a solid mass which occupies a large portion of the body- 
