1885.] Entomology. 179 
The author describes in some detail the arrangements of the 
muscles of the legs; the nerve-cord supplying them is pretty 
stout, and the large number of filaments sent to the joints of the 
tarsus lead to the supposition that these have a tactile function; 
the nerve-fibers are seen to enlarge into thick spindle-shaped 
ganglia. There are two tracheal trunks. 
The prime function of the leg is locomotor, and insects move 
through gaseous, fluid and solid media. The last is seen in 
fossorial forms, of which Gryllotalpa may be taken as the type; 
here some of the joints are flattened out and provided with 
teeth, and the muscles are well developed. 
In some cases, legs of a fossorial type are possessed by insects 
which move on the ground, but the larve of which are subterra- 
nean in habitat. The water-beetles and aquatic Rhynchota have 
the legs converted into swimming organs; they are widened out 
into plates, and provided at the sides with movable hairs, which 
are directed slightly backward. The median pair of legs in Corixa 
is provided with two very long hooks, the function of which is to 
x the animal at some depth among the water-plants, and so to 
prevent its floating upwards. 
In the aérial forms, we have first to notice those that move on 
the surface of the water; in these the legs are often provided with 
considerable enlargements of the tracheal trunk, by means of which 
they are enabled to float. Others have very long legs, by which 
they can balance themselves and extend over a large surface of 
the water; the lower surface of the tarsal joints, or that which is 
in contact with the water, is provided with thick hairs. In some 
Diptera hairy lobes are developed. Arrangements for climbing 
are very widely distributed, and are very various in character; 
the most common are hooks, which by their sharp tips are able to 
enter the smallest depressions, and so obtain a firm hold; some- 
times they are pectinate and enabled to catch hold of fine hairs. 
In very many cases there are organs of fixation; in the locust 
they have their chief mass made up of a large number of free 
flexible rods (not tubes). The periphery is occupied by scales 
which correspond in number to the rods, with which they appear 
to be connected by fibers; the space between the rods is filled 
with a fluid. Below these are groups of spindle-shaped cells 
which appear to be glandular in character. The fixing surface of 
the Hymenoptera, Neuroptera, and Lepidoptera consists of an 
impaired lobule placed between the hooks; their structure is most 
complicated in the first-named order. Observations on Vespa 
crabro did not result in the detection of any space which could be 
regarded'as a vacuum. The lower surface of the lobule is soft 
and almost smooth; a few short hairs may be developed at its 
base; below this is a hard chitinous mass with stronger hairs. 
The upper surface is either covered with hairs or is finely folded. 
Near the base is a chitinous plate carrying a pair of strong sete. 
