the egg-cases and early stages of some Cassididm. 21 



and hardening rapidly when exposed to the air. The 

 rapidity with which it becomes hard is remarkable, and is 

 more marked than it is in the case of chitin. Lecaillon, 

 whose paper on the envelopes of the eggs of Chrysomelidie, 

 in Arch. Anat. micr. II, 1898, has already been referred 

 to, tells us that, in conformity with the views of Ticho- 

 mirofif, he considers the chorion of eggs to be formed of a 

 peculiar substance — chorionine — very different from chitin. 

 In ChrysomdidcV he distinguishes two forms of epichorion — 



(1) excrementitial coverings, e. g. Clytlira, Gryptocephalus, 



(2) epichorions composed of special secretions. These secre- 

 tions he thinks to be of two kinds : (a) derived from the 

 epithelium of the genital ducts and passages ; {V) from 

 special glands. In OassididcV both excrementitial and 

 glandular coverings are applied to the eggs, and the 

 glandular part of the epichorion comes from a special gland. 

 Nothing appears to be known as to the chemical properties 

 of these very remarkable glandular epichorions. It is 

 possible that they may prove to be some special kind of 

 chitin. 



Postscript. — According to a paper communicated to the 

 Society by Captain Williams and published by the Society 

 in this Part of the Transactions, the egg-case in Mantidie 

 is composed of two substances of dissimilar nature. The 

 material of which the central part of the ootheca is formed 

 appears to be like that used by Aspidomorplia. The foam 

 that is concomitantly used by the Mantis is constantly 

 brushed away from the middle to the sides, and finally 

 forms an outer covering to the egg-case. Cf. Williams, 

 p. 180, postea. 



Explanation of Plates I — Y. 



Plate I. 



Fifl. L Ootheca of Aqu'domorpha pn)icticosta attached to a leaf of 

 Ipomaa pescapree ; seen laterally, x 2. 



2. Horizontal section of same, x 3. In one of the series of 



chambers eggs, in section, are seen. 



3. Perpendicular longitudinal section of same. x 3. 



4. One of the membranes of which the ootheca is composed, 



separated with its attachment to the egg. x 4. 



