26 Transactions of the Society. 



and above these numbers is less frequent. One female in confine- 

 ment laid three or four eggs on June 16, but the batch was not 

 completed till the 25th, when it consisted of forty-five eggs. 

 Thus, on an average five eggs per diem were laid. The first 

 nymphs hatched out on July 25, the last on August 8, or, roughly 

 speaking, the nymphs hatch out in about 40 days. The number 

 of antennal joints in the just-hatched female nymph is nine ; the 

 number of adult joints appears to be twenty-two. I have not run 

 the nymphs through from hatching to adult, but they must take 

 a long time maturing, since a batch which hatched on April 26 

 are still (September 10) not yet adult. I have not noted the 

 moults, but believe they devour the shed skins, as they certainly 

 eat away some of the eggs soon after hatchiug. 



There is no revolution of the embryo, the head throughout 

 development remaining on the ventral side of the egg, although 

 the embryo changes its position. The primitive band at first forms 

 about the middle of the ventral side of the egg (Plate III, fig. 1), 

 but later the head moves towards the posterior pole, and the band 

 grows around the pole and up the dorsal side of the egg. It soon 

 reaches nearly to the anterior pole, and the posterior end of the 

 band recurves (Plate III, fig. 4), whilst the head is in its lowest 

 position at the posterior pole of the egg. At this time the 

 appendages have already budded out, the antenna? and labrum 

 being first distinct, afterwards the mandibles and maxilhe, and 

 finally the legs. The labrum is at first very markedly lobed 

 (Plate III, fig. 4). The amnion and serosa around the head region 

 of the embryo are in close contact, but early in the recurved stage 

 the posterior part of the embryo sinks somewhat back into the 

 yolk, so that — except around the head region — there is yolk 

 between the amnion and serosa. At a later recurved stage the 

 serosa secretes a complete outer membrane (Plate IV, fig. 5, 

 section i-j) which separates from the serosa. The amnion tears 

 or disintegrates down the median ventral line of the embryo and 

 commences growing afresh laterally and dorsally, fusing to the 

 dorsal remnant of the serosa (the ventral part of which disinte- 

 grates as well as the ventral part of the amnion, the remains — 

 together with some yolk which was enclosed between the amnion 

 and serosa — forming the secretion in which the appendages of the 

 embryo are embedded up to the time of hatching). The dorsal 

 remnant of the serosa thus serves to surround the yolk whilst tiie 

 amnion grows around and encloses it, which it quickly does, and 

 the amnion itself is soon followed up by the ectoderm, which 

 quickly encloses the whole yolk : the remains of the serosa and 

 amnion gather dorsally near the head (Plate IV, fig. 7a), and are 

 absorbed into the gut with the remnant of yolk as the ectoderm 

 closes over and completes the back of the embryo. But the total 

 absorption of the amnion and closure of the ectoderm over the 



