214 NEW YORK STATE MUSEUM 



The head when dissected out of the pro thorax shows a me- 

 dian blackish hne, 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, 111., 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 heaA^y 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 sidewnse, 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 G e r a n o m y i a 

 canadensis and with numerous midges and micro-caddis 



