"^^ AND ^{'^ 



JOURNAL OF VARIATION. 



No. 9. Vol. III. September 15th, 1892. 



THE GENUS ACRONYCTA AND ITS ALLIES. 



By Dr. T. A. CHAPMAN. 

 {Continued from page 149.) 



\pMA ORION. — This is the only British species out- 

 side the genus Acronyda that appears to me to 

 belong to the same family. I presume it was 

 originally classed with Acrojiycta on the ground of 

 characters of the imago, I sustain its claim to that position 

 because the newly hatched larva presents an eleventh segment 

 that has essentially the same characters as that segment has 

 in true Acronyctas. The young larva has, nevertheless, a 

 considerably different facies, and the egg is nearly spherical, 

 instead of being of the flat form characteristic of those of 

 Acronycta. Nevertheless, the egg has the same remarkably 

 fragile delicacy that many Acronycta eggs have. 



The egg (PI. VIIL, fig. lo-ioa) is flat on the lower surface 

 on which it rests and so is not quite a sphere, but is nearly 

 three-quarters as high as it is wide. Its diameter is 0*7 mm., 

 the ribs number thirty at the margin, and the transverse or 

 secondary ribs are very marked, from the netting at top, the 

 ribs increase outwards by division and intercalation in the 

 usual way, but, instead of doing so in irregular positions, 

 nearly all the increase takes place at about one-third of the 

 way from the summit, though rarely quite as regularly as 

 shown at fig. loa. The whole egg is extremely delicate and 

 transparent, acquiring a pale straw tint, but no deeper coloration 

 or markings, nor does any change occur as the contained larva 

 becomes ready to hatch, except a slight increase of opacity and 

 the tips of the larval jaws can be seen, but the young larva is 

 itself so transparent that very close observation is necessary to 

 see anything more of it. 



