DIPTEIIA. 
501 
organs pass with little or no alteration into the imago. Fatty 
body none or inconsiderable. Pupa-state short and active. 
^^Type Musca : — The thorax and head of the imago are produced 
independently of the corresponding sections of the hypodermis of 
the larva, and the abdomen alone directly by the conversion of 
the eight hinder larval segments. The thorax and head, with 
their appendages, are develo})ed from imaginal disks, which are 
of embryonic origin, and are firmly attached in the interior of 
the body-cavity of the larva to nerves or trachcie. It is only 
after the formation of a cask-like pupa-shell from the chitinous 
skeleton of the larva that the imaginal disks coalesce to form the 
thorax and head. Destruction of all the larval systems of organs, 
either total or by histolysis. New formation of them with the 
aid of the granular globules produced from the breaking-up of 
the fatty body. Genital glands indicated in the embryo, and 
gradually developed. Pupa-state long- continued and with latent 
vitality.^^ 
As the two types are most clearly discriminated by the pre- 
sence or absence of true imaginal disks, the author suggests 
that the metabolic insects might be divided into the two primary 
groups, Insecta discota and adiscota. 
Walker (Journ. Linn. Soc. ix. pp. 1-30) publishes a table of 
the distribution of the species of Diptera collected by Wallace in 
the Eastern Archipelago. The numbers of species in the different 
localities are as follows : — Malacca 51, Singapore 67, Borneo 129, 
Celebes 236, Amboyna 50, Am 166, Batchian 75, New Guinea 
70 or more. Walker has seen about 300 species from the Phi- 
lippines, many undescribed. In the introductory summary 
Walker refers to the different families and to the peculiarities in 
their mode of representation in the islands. 
Loew (Zeitsekr. ges. Naturw. xxiii. pp. 336-347) has noticed the Diptera 
haunting the salt-springs and other saline localities of the neighhourhood of 
Diirrenhorg. Tho spocios ohsorvod by him, and of tho habits of which ho 
gives a more or less detailed account, were : — Lispe cmssiuscula.] Ilahnopota 
salinaria (the larva of which lives in the evaporating- troughs of the salt-works, 
and the oeconomy of the insect is described at some length, 1. c. pp. 337-343) ; 
Ephydra riparia (the larvae found with those of the preceding species) j 
Thinophilus jiampalpis (Zett.) ; Medeterus tenuicauda (Loew) ; and a new 
and peculiar species of Atissa. 
Loew communicates (Zeitsch. ges. Naturw. xxiv. pp. 377-396) the results 
of 4 mornings spent in collecting Diptera on the Ziegelwiese near Hallo in 
the second half of July 1864. The number of species obtained by him was 
185, several of which ( Ceratopogon, Campsicnemm^ Tetanocera) are described 
as new. The paper includes synonymic notes on several of the other 
species. 
SiEBKE (Entomologiske Undersogelser, 1866) gives a list of the Diptera 
