330 AMERICAN PSYCHODIDiE. 



to sustain life for any considerable length of time. While feeding 

 the larva usually allows the tip of the tube to extend out of the 

 water, and when it descends into the water it is seen to throw off 

 bubbles of gas and invaribly returns to the surface after a very 

 short time. 



The segmentation is rather indistinct in living specimens, espe- 

 cially in very young and some of the old ones. In cleared speci- 

 mens the three thoracic and eight abdominal segments can be clearly 

 made out. The annulation is much less distinct than in Pericoma 

 canescens. The fifth and sixth abdominal segments each have three 

 distinct annuli and the seventh two. The remaining abdominal 

 and thoracic segments are without distinct annuli. There is no 

 marked break between the abdominal and thoracic regions of the 

 body. The body is all covered with very fine, spine-like cilia, 

 together with one or two long hairs on each side of the segments. 

 The head is dark brown in color, which makes it quite difficult to 

 detect the small, black pigment eye spots. The antennae appear to 

 consist of tufts of plates as in P. canescens. The central part of the 

 body is opaque, due to the presence of great quantities of food in the 

 alimentary canal. The anal breathing tube is usually heavily 

 charged with dark pigment, especially at the tip. The annuli of 

 • the fifth and sixth segments and the second annuli of the seventh, 

 together with the eighth segment, are each armed above with a 

 small, chitinous shield. These shields decrease in size anteriorly 

 and are entirely absent on the anterior segments. The adult larva 

 is about 8 mm. long, and varies in diameter from about .6-1.3 mm. 

 They are usually not so slender as the specimen figured. 



PUPA. 



The pup?e are found concealed in the debris at the surface of the 

 water, where their prothoracic breathing tubes extend above the 

 surface. They are relatively active, being able to move quite freely 

 by the lashing of the abdomen. The transformation from the adult 

 larva to the pupa has been found to take place within twelve hours. 

 The pupa, as is seen from the figures, possesses a girdle of conspicuous 

 spines on each abdominal segment, especially the posterior one, 

 together with two curved ones on the tip of the last segment, which 

 aid in locomotion. The eyes, antennse, wings and legs are all dis- 

 tinguishable on the surface. The thoracic breathing tubes are long 

 and flexible, with a short, much wrinkled stalk, and a wider, cylin- 



