JVNT) 
JOURNAL OF VARIATION. 
No. 4. VoL. II. 
THE GENUS ACRONYCTA AND ITS ALLIES. 
By Dr. T. A. CHAPMAN, F.E.S. 
{Continued from page 31.) 
CRONYCTA (Cuspidia) psi. — Psi'xs in many respects 
so like tridens that having fully described those 
aspects of that species to which I have paid most 
attention, psi may be most conveniently treated by 
noting the points of distinction between them, rather than by 
going into a fully detailed account of each stage. Psi is the 
only Acronycta of which it has happened to me to meet with 
the egg as laid naturally by the moth in the wild state. This 
egg was found on July 4th, 1888, laid on the upper surface of 
an oak leaf, the diameter was .97 mm., and the height about 
.33 mm. ; it had 51 ribs, of a pale straw tint or almost 
colourless. An egg laid in captivit}^ on a glass slide measured 
1.03 mm. in diameter and had 50 ribs, other specimens had 
54 ribs. It is thus seen that the egg is distinctly larger than 
that of tridens, and has a larger number of ribs ; in colour (or 
want of colour) and other characters they are very much the 
same; in the figures (PI. VIII., fig. 1, psi ; 2, tridens) the 
difference in colouring represents the different method taken 
by the artist, at different times, to show the glassy trans- 
parency of the eggs, and does not correspond to any actual 
difference of tint in the eggs themselves. These two eggs 
exhibit perhaps more distinctly than any others, what is very 
obvious in all Acronycta eggs, and is common to all eggs of 
Lepidoptera so far as I have observed them, viz., that the egg 
contents shrink away from the shell in a very early stage of 
development, leaving a space containing only a clear fluid 
between, and the flatness of these eggs leaves this space very 
evident as a margin round the contents, and in the species with 
June 15th, 1891. 
