21G THE entomologist's record. 



time of laying, such abnormal depressions are very clearly marked, 

 and the general contour of the eggs is maintained. The characteristic 

 oval depression, seen in the upper surface of most Geometrid 

 eggs, is rather well marked, and moderately large. The surface of 

 the egg is smooth, finely pitted at the micropylar end. The oval 

 depression is placed well towards the micropylar end. There are 

 faint traces of irregular ribbing towards the curved edge of the same 

 end. The shell is very transparent, and the egg-contents also inclined 

 to be so. 



Eijii iif T. crcpmtularia (7 days old). — The e^g of T. crepiiscularia 

 is, to the naked eye, of a pale pea-green tint with a suspicion of 

 blue in it. It is oval in shape {i.e., of the shape of a hen's egg). 

 The eggs are peculiarly constant in size, with an oval depression on 

 the side nearly midway between the micropyle and its nadir. The 

 micropylar area is covered with a distinct pitting, although the shape 

 of the micropylar cells are difficult to make out. The micropylar 

 area occupies a considerable portion (about two-thirds) of the broad 

 end. There is no trace whatever of ribbing. The egg-shell is not 

 transparent. 



(Jou)parisnji of tlw ci/// of T. histortata irith that of T. crepmcularia, — 

 The comparison of these eggs is a very easy matter, for they differ in 

 several particulars. As they rest side by side under the micros- 

 cope, the larger size of the egg of T. histortata is very evident. It 

 has about double the cubical contents of that of T. crcpusnilaria. 

 The colour of the egg of T. histortata is now (under the microscope 

 with a good light) of a pale pearly whitish green, that of T. crepiis- 

 cularia of a dull yellow hue, in which there is scarcely a trace of 

 green. This is particularly interesting, considering how nearly of 

 the same tint they appear to the naked eye. In shape, too, the two 

 sets of eggs are very different. The shape of the egg of T. histortata 

 is not unlike the long cylindrical eggs, with almost equal rounded 

 ends, so characteristic of many Geometers ; that of T. crcpusnilaria 

 resembles somewhat a hen's egg in shape, with one end much fuller 

 than the other. The outline sketches (drawn to scale) from the two 

 lots of eggs, as they lay side by side in the field of the microscope, 

 will give a better notion of the difterence in shape and size than any 

 amount of description will do. The egg-shell of both species is very 

 smooth, but that of T. histortata is shiny and somewhat transparent, 

 whilst that of T. crepiuicularia is dull and opaque. The depression 

 on the upper side of the eggs is placed near the micropylar end in 

 T. histortata ; that of 2'. crcpiiscnlaria is placed near the centre of the 

 upper surface. The shell of T. histortata is irregularly wrinkled longi- 

 tudinally ; no such wrinkles are observable in the egg of T. crcpusm- 

 laria. The micropylar area of T. histortata is a marked depression, 

 that of T. crcjiuscularia is spread over the convex surface of the broad 

 end of the egg. It is most interesting to have had the eggs of the two 

 species side by side for examination. I am quite open (and so is my 

 friend Mr. Baty, who has made the microscopical examination with 

 me) to separate normal eggs of these species from each other. 



I strongly suspect that the difference of colour— the more yellowish 

 tint of T. crepu.scidaria— in the early stage, is due to a real difference 

 in the embryonic development of the egg, and not to the difterence of 

 age, for the 2\ crepiiscularia eggs were five days newer than those of 



