No. 413.] DEVELOPMENT OF THE DIPTERA. 367 
of larval organs as is apparent in the pupa of Calliphora, where 
the pupal body cavity is filled with * pseudo-yolk," a confused 
fluid mass of degenerating tissue. 
The larvae of Blepharocera capitata! are of extraordinary 
external appearance, and. in their habits and structure are 
widely removed from other dipterous larva. They live under 
water in brooks, clinging by six elaborately developed ven- 
tral suckers to the smooth rock bed or to smooth stones in 
parts of the stream where 
the water runs swiftly and 
is shallow. The segments 
of the body are greatly 
modified, the three thorac- 
ic segments and the head 
being fused to form a single 
large anterior body region. 
For the control of the 
suckers and for the peculiar , 
lateral swinging movement & 
of the body in locomotion 
an elaborate musculation is 
developed, which is very 
different from the muscu- 
lation of the adult fly. The 
Pup: are also extraordi- 
nary in character and live, 
like the larvze, attached to T E 
the rocks in swift, shallow fic. 2,—Larval muscle of Blepharocera capitata, 
Put&'of the strehimi "The. e een A pepe n der dem o 
duration of the pupal stage is fifteen days. The histolysis of 
the larval tissues begins three or four days before the true 
pupal condition is reached. The larvae cease feeding, become 
quiet, and thus remain three or four days before pupation. 
The total duration, therefore, of the time devoted especially to 
the change from larva to imago is about eighteen days, as 
compared with twelve in the case of Holorusia. 
! For an account of the structural character of the larvæ, see Kellogg, Notes on 
y Life-History and Structure of Blepharocera capitata Loew, Ent. News, vol. 
xi (1900), pp. 305-318. . 
