ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
305 
insect larvae of the same species which under the influence of different 
factors are formed differently to one another, while the imagines exhibit 
the same form. The latter case is an example of what the author has 
already called poecilogony. It is often difficult to determine with which 
phenomenon one lias to do. Anatomy and embryology will enable us to 
distinguish the converging species of different genera. When such 
species belong to the same genus we find that in one locality there 
is no fruitful sexual intermixture between them ; on the other hand 
a fruitful crossing is evidence of poecilogony. An interesting example 
of poecilogony is exhibited by a coprophagous fly, Musca corvina , which, 
according to Portchinsky, lays, in the north of Kussia, 24 eggs, the 
development of which breaks up into two sharply distinct periods. In 
the south, on the other hand, the same fly lays only one egg and the 
development is much simplified. 
Specific Stability.* — Mr. F. Galton has made some suggestions to 
the Entomological Society which appear to be of considerable im- 
portance. He asks for information on — (1) Instances of such strongly 
marked peculiarities, whether in form, in colour, or in habit, as have 
occasionally appeared in a single or in a few individuals among a brood. 
(2) Instances in which any one of the above peculiarities has appeared 
in the broods of different parents. (3) Instances in which any of these 
peculiarly characterised individuals have transmitted their peculiarities 
to one or more generations ; especial mention should be made whether 
the peculiarity was in any case transmitted in all its original intensity, 
and numerical data that showed the frequency of its transmission would 
be particularly acceptable — (a) in an undiluted form ; (6) in one that 
was more or less diluted ; and (c) of its non-transmission in any 
perceptible degree. The author appends a list of his various memoirs 
which bear on this subject. 
Classification of Lepidoptera. t — Mr. Y. L, Kellogg draws attention 
to the new provisional classification of the Lepidoptera which has 
been proposed by Prof. Comstock, and adds a few notes of observations 
which seem to be confirmatory of the most conspicuous feature of this 
Li new classification. The author calls attention to an essay by himself 
I on the taxonomic value of the scales in Lepidoptera.:}: He thinks that 
the structure of the thorax in the Jugatae, though not distinctly available 
If! as a recognition character, has considerable phylogenetic significance, 
[ti and he is of opinion that a careful study of the thorax of the Lepidoptera 
a must certainly be rewarded by suggestive results. 
From a wide point of view there is, in the development of any con- 
jt siderable group of organisms, as for example, the class Insecta, a general 
jjjfi tendency of specialisation along some pretty definite main line, or more 
or less nearly parallel lines. We may cite in the Insecta the develop- 
ment of the flight function accompanied, in the Lepidoptera, by the 
specialisation of the front wings and a reduction of the hind wings as 
' well as by a specialisation of the thorax. Subordinate to any general 
tendency such as the development of the flight function, there will 
* Trans. Ent. Soc. Lond., 1895, pp. 155 and 6; Nature, li. (1895) pp. 570 and 1. 
t Amer. Natural., xxix. (1895) pp. 248-57 (1 pi.). 
X Kansas Univ. Quarterly, iii. (1894) pp. 45- S9. 
1895 
X 
