THE CRANE-FLIES or NEW YORK PART II 741 



gills are completely everted. The specimens should be placed in 4-per- 

 cent formalin or, preferably, 70- to 75-per-cent alcohol. Large, fleshy 

 larvae, such as those of the Tipulinae, should be slit at the third or the 

 fourth abdominal segment to allow easy penetration of the preservative. 

 Other notes on preserving material are given by Banks (1909) and by 

 Williamson (1916). 



Study 



In the study of the gross material, both the binocular and the com- 

 pound microscope may be used. A special word on the preparation 

 of the head capsule of the larva may be helpful. In removing the head 

 capsule from the body it is generally easiest to slit longitudinally the tho- 

 racic segments back of the head and pull the capsule thru this incision. 

 In forms with compact and massive capsules, the thorax and the head may 

 be snipped off and the head everted after the manner of turning the 

 finger of a glove. The capsule should be left in a 5-per-cent solution 

 of caustic potash until all the fleshy parts have been removed. It 

 should be dissected out so that all the mouth parts are isolated and 

 rendered distinct for study. Then follow the usual processes of washing 

 and dehydration, and the final mounting in Canada balsam. 



Various means are available for examining the spiracular disk. The 

 specimen may be placed in a watch crystal under water and held firmly 

 in place by a piece of glass, as, for example, a broken microscope slide. 

 By holding a heavy piece of glass over the anterior end of the body, the 

 posterior end may be bent at a righ't angle and bolstered in place by two 

 or three other glass fragments so that the disk is directed straight upward 

 and its details are easily examined. Other methods, such as embedding 

 the anterior end of the larva in paraffin in a deep dish and submerging 

 the body, may be followed. It must be emphasized that in alcoholic 

 gross material the study should be conducted under alcohol or water. 



The measurements of the pupa abbreviated in the text as d.-s. 

 (dextro-sinistral) for the width and d.-v. (dorso-ventral) for the depth 

 are taken opposite the wing pad. 



Rearing 



In order to rear the immature stages of crane-flies successfully the 

 natural haunts should be imitated as closely as possible. In the case 

 of wood-inhabiting species, large pieces of the material in which the larvae 



