ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
423 
stream at Mean wood, near Leeds. The larva feeds upon green Algae and 
is found entangled in the filaments. It breathes air and often creeps 
out of the water altogether. The larva is described as having a body 
8 mm. long, which consists of a head followed by eleven segments. 
The body is densely covered with chitinous tubercles, which for the 
most part are very minute. These appear under the Microscope like 
nails imbedded in the flexible skin. This external armour is a great 
obstacle to anatomical examination, and no doubt protects the living 
animal either from the attacks of its enemies or from abrasion. The 
more exposed parts of each ring of the body are protected by chitinous 
shields in addition to the tubercles. The dorsal shields of the first 
three annuli are divided along the middle line. The use of this 
arrangement is clear at the time of pupation, when the integument splits 
along these annuli to allow of the escape of the pupa from the larval 
skin. The sides of the body bear a flexible armour of regular and close- 
set setae. There is a lateral fringe of much longer setae, all of which 
point backwards, and so appear to be able to save the larva from being 
swept away by a sudden rush of water. Unlike most aquatic dipterous 
larvae, this species is provided with anterior as well as posterior spiracles. 
The two pairs of anal processes consist of a stout chitinous rod, bearing a 
fringe of fine filaments, which project from the sides and tip. The anal 
processes stand out from a dorsal projection which overhangs the anus. 
Each filament is set with very fine hairs, so that it somewhat resembles 
a plume. The larva may often be seen to run the anal filaments through 
its mouth, thus cleansing them from diatoms, desmids, &c., which are 
probably devoured. The larvae seem most at home in water just deep 
enough to cover the body. They then bury themselves in mud, sand, or 
Algae, bringing the tip of the abdomen to the surface of the water. The 
outspread filaments of the four processes then form a cup, filled with 
air, and from this air can be taken into the spiracle. If this tranquil 
mode of life be interrupted by heavy rain causing a sudden deepening of 
the water and a great increase in the force of the current, the larva will 
either cling to the weeds and remain submerged for hours, or it wil 
leave the water altogether, and creep upon the wet herbage, or if the 
water be still, it can float on the surface. In any case, it can keep up a 
certain amount of respiration and prevent its spiracles from being wetted 
with water. The authors make an interesting comparison between this 
and other aquatic larvae, and the paper concludes with a valuable critical 
account of the literature and the early stages of the Psychodidae, for 
which the authors are indebted to Baron Osten Sacken. 
Amitosis in Ovaries of Hemiptera.* — Herr F. Preusse has investi- 
gated the ovaries of Nepa cinerea and some other Hemiptera. There is 
no doubt that amitosis plays an important part in the multiplication of 
cells both in the young stages and in the older follicles. In the younger 
egg-chambers, mitoses also occur abundantly, but no transitional forms 
were observed. The author cites other cases in which amitosis is of 
functional importance. 
Cecidomyia Avenae sp. n.f— M. P. Marchal finds that Cecidomyia 
destructor Say does not develop on oats, while the new form which he 
* Zeitschr. f. wiss. Zool., lix. (1895) pp. 305-49 (2 pis.). 
f Comptes Bendus, cxx. (1895) pp. 1283-5. 
