214 NEW YORK STATE MUSEUM 
The head when dissected out of the prothorax shows a me- 
dian blackish line, dilated behind where it joins at the rear of 
the head, and shorter, blackish, paired stripes that lie upon the hind 
angles externally. The length of the head is three times its 
width. ‘The blackish mandibles are armed internally with about 
five teeth among which are two longer ones that alternate with 
three shorter ones. The maxillae are shorter than the mandi- 
bles, and each bears a bunch of fleshy processes upon its tip. 
Life history of Dicranomyia simulans Walk 
This common and widespread species is found about wet logs 
on the edges of streams, and on wave beaten shores. I had an 
excellent opportunity for observing its life history and habits 
at Lake Forest, Ill., during several weeks of the latter part of 
the summer of 1906. It is abundant on the piers along the 
west shore of Lake Michigan, and the “Ferry Hall Pier” at 
Lake Forest was conveniently near the cottage in which I was 
living. This pier was built on heavy driven piling, covered 
outside with heavy plank. About three feet of surface was ex- 
posed above the water at its normal stage. The planks were 
old, and sheltered a scanty growth of short, stemmed mosses 
in the cracks, and bore a heavy fringe of Cladophora and other 
algae just below the water line, with a film of “skin algae” 
extending a little higher. 
All over the sides of the plank, in either sun or shade, the 
adult simulans could be seen throughout the summer 
months, sometimes in considerable numbers. I was first at- 
tracted to notice them by their habit of running rapidly side- 
wise along the pier; and their resemblance to harvestmen 
(Phalangidae). They run habitually sidewise, apparently rarely 
moving forward except to escape an obstruction, and very rarely 
appearing on the top of the pier. They rest in an inverted po- 
sition on the under surface of the overhanging plank on the 
top of the pier. They stick to the surface so persistently 
that it is difficult to make one take flight; they may be driven 
all about on the surface, or poked with a stick; they can fly 
well enough when they will, but when induced to fly they 
settle again almost at once, and within a few feet of their 
starting place. 
They are associated upon the piers with Geranomyia 
canadensis and with numerous midges and micro-caddis 
