ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
535 
Frenulum of Lepidoptera.* * * § — Mr. G. 0. Griffiths gives a careful 
account of this apparatus for connecting the fore- and hind-wings of 
many Lepidoptera during flight. It is analogous in its purpose to the 
less perfect jugum of the Trichoptera and Micropteryx , to the wing- 
hooks of the Hymenoptera, and to the locking apparatus of Belostoma. 
Seasonal Dimorphism in Precis.f — Mr. G. A. K. Marshall has 
been able to demonstrate by breeding, what he concluded from field 
observations, that P. sesamus is the dry-season form of the wet-season 
P. octavia , “ the most remarkable instance of seasonal variation as yet 
known among the Lepidoptera.” He gives the details of the case, and 
discusses the theoretical interpretation. His own view is that the 
tendency to variation was initiated by climatic influences, especially 
humidity, and subsequently utilised and developed by natural selection 
for protective purposes. 
Affinity of Wild and Domestic Silkworms.^— Prof. C. Sasaki dis- 
cusses the wild silkworms of Japan. They agree entirely with Theo- 
pTiila mandarina , as described by F. Moore. From this species the 
domestic silkworm has been derived. 
Metamorphosis of Caterpillars.§ — M. Arnold Pictet describes the 
way in which the imago emerges from the’ chrysalid state, and the 
various symptoms of the near approach of emergence. The process 
may be hastened by mechanical excitation and by raising the tem- 
perature. 
Metamorphosis of Muscid8e.|| — Sig. A. Berlese describes the wander- 
ing cells (trophocytes) which occur in great numbers in the pupae of 
Muscidae, and serve to store up the albuminoid detritus resulting from 
the disruption of the larval organs. The store may be compared to a 
second yolk, accessory to the new development. 
Alleged Phylogeny of AphanipteraA — Dr. B. Wandolleck criticises 
Dahl’s theory ** that Puliciphora lucifera g. et sp. n. is a connecting link 
between Pulicidae and Phoridse. A comparison of the adults and the 
larvae reveals insurmountable difficulties against any such conclusion. 
The Aphaniptera are indeed not far from the Diptera, but cannot be 
derived from them. Prof. Dahl,j"(' who handed over his material to 
Dr. Wandolleck, makes a brief rejoinder. 
Defensive Glands of some Beetles4| — L. Bordas has studied the 
anal glands of Cybister Rceselii Fabr., Dytiscus marginalis, &c. They 
are large but simple glands, with a pyriform collecting vesicle and an 
excretory duct. The secretion is green and has a sickening smell. As 
the glands do not open into the gut, they can have nothing to do with 
digestion. They may have some excretory significance, but there is no 
doubt that they are defensive. 
* Trans. Entom. Soc. London, 1898, pp. 121-32 (1 pi.). 
t Ann. Nat. Hist., ii. (1898) pp. 30-40. 
X Annot. Zool. Japon., ii. (1 898) pp. 33-40 (1 pi.). 
§ CR. Soc. Phys. Nat. Geneve, in Arch. Sci. Phys. Nat., v. (1898) pp. 577-9. 
|| Riv. Patol. Veg., vi. (1897) pp. 111-4 (1 pi. and 1 fig.). 
H Zool. Anzeig., xxi. (1898) pp. 180-2. ** Op. cit., xx. (1897) pp. 409-12. 
ft Op. cit., xxi. (1898) pp. 308-9. 
XX Comptes Rendus, cxxvi. (1898) pp. 1824-5. 
