146 



THE ENTOMOLOGIST S RECORD. 



to the surface of so small a stem, the terebra of the insect has to be 

 bent into a corresponding curvature. The cuticle, beneath -which it 

 works, seems to be strong enough easily to hold the saws to this curve. 

 Until one sees that there is and necessarily must be this curvature, 

 there is nothing in the actual working of the saws to suggest that it is 

 so, and certainly it causes no impediment to their operation. One 

 observes nothing to suggest, as something actually seen, this curving 

 of the terebra whilst it is at work, but as it is for its whole length 

 equally visible through the very transparent cuticle, it is obvious that 

 it follows the curve of the surface between the cuticle and the under- 

 lying tissue. 



(See pi. v., fig. 5, diagram of transverse section of stem of Cimral- 

 laria, with the incision of Pliymatocera, through an egg, showing how 

 the incision curves round the stem, the thinness of the raised cuticle, 

 and the position of the egg, not quite at the bottom of the incision.) 



The attachments of the bases of the saws and supports to the abdo- 

 men are much more visible than in TricliioHoiua, and so the movement 

 of the saws may be gathered almost as well by watching the move- 

 ments of the parts at the extremity of the abdomen. 



The posterior margins of the supports for a portion of their basal 

 halves are soldered together, unlike the saws, each of which can move 

 independently of the other, of course only through a small distance. 



The fly begins her operations by penetrating the cuticle and 

 advancing the terebra beneath it for half its length (pit. v., fig. 1, ^), 

 then it cuts in the direction in which the saws face, till it arrives at 

 the position Fig. 1, ^. It then carries the terebra back towards 

 position ^, with the apex all the time within the slit, as indicated in 

 fig. 1, 3, until it reaches the place shown in fig. 2, ^, some way short 

 of position ^. It then descends to the depth of position ^. It now again 

 cuts, may we say, downwards as suiting the diagrams, and also as being 

 away from the body of the insect, for the same distance as in the first 

 incision (fig. 1) that is, about half the length of the terebra, to the 

 actual position shown in fig. 2, ^. It then cuts very similarly to 

 the previous cut (fig. 1), passing through the positions shown in 

 fig. 2, 5, g, ^. The terebra then returns from position 2, ^, to position 

 2, 4, passing along with only the tip within the incision, as shown in 

 fig. 1, 3. It now descends into position fig. 3, ^, which is practically 

 identical with position 2, ^. The first Qgg is now laid, in the position 

 shown in fig. 4. The terebra is now withdrawn but not so far as 

 fig. 1,3, but only as far as fig. 3, 0, is then carried across the top of 

 the egg and descends into position 3, j^j which is identical with the 

 position 2, ,, but is really, the same position as regards the second 

 egg, as fig. 2, ^ was with regard to the first; the space for the second 

 egg is cut as indicated in fig. 3, precisely as that for the first was done, 

 as shown in fig. 2. Again, the terebra is brought back, in the way 

 shown in fig, 1, 3, and the second egg is laid, and so on. 



The laying of the egg is very like that noted in Tric/ti<>so»ia, after 

 a short rest some heavy movements occur at the base of the terebra 

 and at the extremity of the abdomen, and almost immediately the egg 

 appears. It has much the effect of a conjuring trick. 



At the margin of the saws at their lower cutting half, opposite the 

 arrows as shown in fig. 3, g, the edge of the egg appears and gradually 

 passes forward till it reaches the position shown in fig. 4. It seems to 



