tkaksfor:\iations of the chameleon-fly. 616 



Ckameleon-fly {Stratiomys Chameleon) has been so tersely and 

 fully given by Mr. F. Walker in his ' Insecta Britannica,' that 

 I cannot do better than transfer his account to these pages : — 



' These flies feed on the honey of flowers, and ai3pear in the 

 spring and in the summer on aquatic plants : their flight in 

 hot weather is very rapid, but short, and they quickly return to 

 the spot whence they took wing. The larvce are aquatic, and 

 the metamorphosis of Stratiomys Chameleon has been often 

 observed. 



' Its eggs from white -become green, and then change to 

 orange-green ; they are arranged like tiles on a roof, one laid 

 partly over another, on the underside of the leaves of Alisma 

 plantar/0, the water plantain. The larva often remains 

 suspended by its radiated anus at the surface of the water, 

 with its head downwards. Its ganglions are so near each other 

 as to appear like a string of beads. When it is disposed to 

 sink to the bottom or to descend, by bending the sides of its 

 tail, so as to form a concavity, it includes in them a bubble of 

 air, in brilliancy resembling silver or pearl, and then sinks 

 with it by its own weight : when it would return to the surface 

 it is by means of this bubble. If it moves upon the surface or 

 horizontally, it bends its body alternately to the right and 

 left, contracting itself into the form of the letter S, and then 

 extending itself again into a straight line : by these alternate 

 movements it makes its way slowly in the water. It has much 

 resemblance to some of the Polypi vaginati. The last joint of 

 the pupa retains the exact form of the larva-body, is extremely 

 long, and terminates in an orifice to receive the air, which is 

 surrounded by a circle of about thirty diverging rays, con- 

 sisting of beautifully feathered hairs or plumes. 



' The feathery hairs are so prepared as to repel the water, 

 and thus to suspend the animal by its tail at the surface, and 

 preserve a constant access of air. When it has occasion to 

 sink, it turns these hairs in and shuts the orifice, carrying down 

 with it an air-bubble that shines like quicksilver, and, as 

 is conjectured, enables it again to become buoyant when it 

 wants to breathe. The dorsal vessel (series of hearts, or artery) 

 is attenuated at both ends. The ovaries of the fly are agglo- 

 merate, and the egg-tubes form two bundles, in which the 

 branches are not discernible.' 



