36 ILLINOIS BIOLOGICAL MONOGRAPHS [268 



thorax. The dorsal portion of the head is dark colored while the ventral 

 part of the face is white or yellow. The epicranial stem is absent, the 

 epicranial arms extend cephalad and ventrad from the occipital foramen 

 for a short distance and diverge widely laterad and ventrad; they become 

 obsolete dorso-mesad of the antacoriae. The mouth is directed cephalo- 

 ventrad. The mesothorax, metathorax, and the first eight abdominal 

 segments bear short stout senti from one to five times as long as wide. 

 The prothorax has a distinct parascoli on the caudo-lateral margin of the 

 dorsal shield. There are four or five chalazae cephalad of this parascoli. 

 The caudo-mesal portion of the dorsal shield is provided with a distinct 

 yellow or white shield-shaped area, the cephalic portion of which bears two 

 chalazae adjacent to the meson. The mesal and lateral tergal senti of the 

 mesothorax and metathorax arise from the dorsal shields of their respec- 

 tive segments. The caudal portions of the lateral aspects of the meso- 

 thorax and metathorax are each provided with a small sentus. The meso- 

 thoracic spiracles are located in the mesocoria and the metathoracic spiracles 

 are rudimentary or wanting. The thoracic sterna are all similar, the 

 sternum of each segment has a pair of small verrucae adjacent to each other 

 and the ventro-meson, the coxacoriae are distant. The first to eighth 

 segments of the abdomen are subequal in length. Their terga are pro- 

 vided with four senti arranged in a transverse row; the dorsal senti of the 

 sixth, seventh, and eighth segments have their pinacula fused on each 

 segment, and the dorso-lateral senti of the seventh and eighth segments are 

 short and inconspicuous. The metathorax and the first abdominal seg- 

 ment are each provided with a small cream-colored area caudad of and 

 about one-half the distance between the dorsal and dorso-lateral senti. 

 The lateral aspects of the first and second abdominal segments are white, 

 each with a distinct white lateral sentus and pinaculum; the lateral 

 aspects of the third to eighth segments are cream-colored with their senti 

 and pinacula brown; the lateral aspects of the seventh and eighth segments 

 are without lateral senti but are provided with lateral verrucae while 

 ventrad of each lateral sentus or verruca, except in the first, ninth, and 

 tenth segments, there is a distinct chalaza surrounded by a few setae which 

 represent the paralateral group. The sterna of the first to the eighth 

 segments are similar in shape, except that they become narrower toward 

 the caudal extremity. The first sternum has two ventral ohalazae adjacent 

 to the meson, the ventro-laterals are wanting, while in sterna two to eight 

 the ventral and ventro-lateral groups are present on each segment. In the 

 eighth and ninth segments the ventral and ventro-lateral groups on each 

 side have become fused so that there appears to be a single pair on each 

 side of the meson. The tergum of the ninth segment is longer than wide, 

 shield-shaped, and with many setae on its surface; its lateral aspect is much 

 reduced and bears small and indistinct lateral verruca, the paralaterals 



