of the Oil Beetle, Meloe, and of the Strepsiptera. 337 



dinal suture. Behind these is a free crescentic margin (c), the boundary of 

 the united pro- and n»eso-thorax. This margin conceals the vaginal outlet of 

 the oviduct, which is in the fold between the head and thorax, as stated by 

 Siebold. Its situation is very analogous to that of the outlet of the female 

 reproductive organs in the lulidae and other vermiform Myriapoda, in which 

 the vulva of the female is in the mesothorax. 



I regret that I was unable, through want of specimens, to make so precise 

 an examination as I could have wished of the abdominal viscera of this insect. 

 The abdomen (B) was soft, and divided into eight segments, and so large in 

 comparison with the cephalo-thorax as to resemble greatly that of the pregnant 

 female Termites. I had ruptured it while opening the body of the bee, so that 

 I was unable to determine its precise form ; but noticed however that it was 

 well-supplied with tracheal vessels, the chief of which at the sides near the 

 base, and apparently connected with a large spiracle, as shown by Siebold, 

 were of large dimensions, thus indicating a great extent of respiration. Like 

 the body of the Termites, it seemed to constitute one immense ovary, crowded 

 with thousands of ova of all sizes, in various stages of development, from the 

 immature egg to the Ggg with the embryo almost ready to burst its envelopes. 



The Egg and Embryo of Stylops. 



The smallest ova which presented signs of having been fecundated and the 

 development of the embryo commenced (fig. 23), were of a spherical form, and 

 filled with a dark, yellow-coloured yelk, composed of masses of large nucle- 

 ated cells (a). The yelk was surrounded by a transparent, colourless blasto- 

 derma {b), and on one side (c) was impressed with a transverse sulcus. When 

 measured on a micrometer-plate these ova did not exceed each at most one 

 five-hundredth of an inch in diameter. Multitudes of others, which had not 

 acquired their full size (fig. 24), measured only one thousand five-hundredth, 

 or one two-thousandth of an inch. Those in which the changes had advanced 

 sufficiently far as to indicate, by the doubling of the blastodermic layer on 

 itself (fig. 25, d), a shadowing out of the form of the future embryo, measured 

 about one three-hundred-and-fiftieth of an inch. Others, a little further ad- 

 vanced, in which the outline of the embryo was more distinctly indicated 

 (fig. 26), organization having been carried to that stage in which the greater 



