TRICHOPTERA AND LEPIDOPTERA 



349 



the proctodaeum (Fig. 306 A) is as long as the stomodaeum but with 

 larger lumen. The Malpighian tubes arise at its tip, three on each side; 

 and as they develop, they extend parallel and caudad for about three- 

 fourths of its length. Though origi- 

 nating from a pair of invaginations 

 in the same manner as described by 

 Schwartze (1899) for Lasiocampa, the 

 short basal stem is not evident in 

 Diacrisia. The splanchnic, or vis- 

 ceral, layers of the mesoderm from suboesb 

 which the muscles of the mid-gut are 

 formed are at this time visible as two 

 longitudinal bands of cells extending 

 from the labial head segment caudad 

 to the origin of the Malpighian tubes 

 (Figs. 3075, 308, splm). The mid- 

 gut epithelial strands lie dorsad of the splanchnic mesodermal strands. 

 At 82 hours the closing membrane of the stomodaeum has spread out 

 cup-shaped (Fig. 310). The continuity of this membrane with the mid- 



am 

 sfom 



Fig. 309.— Diacrisia. 

 section of stomodaeum of 77-hour embryo. 

 ilim. m) Limiting membrane, (mge) 

 Mid-gut epithelial ribbon, (suboesb) Sub- 

 esophageal body, (y) Yolk. 



procf 



am 



Fig. 310. — Diacrisia. Sagittal section of 82-hour embryo, (abd) Rudiment of prolog 

 of third abdominal segment, (am) Amnion, (amf) Amniotic fold. (Ir) Labrum. (p) 

 Thoracic legs, (proct) Proctodaeum, obliquely cut. (stom) Stomodaeum. (suboesb) 

 Subesophageal body, (y) Yolk. 



gut epithelial strands is clearly indicated from the sixty-fifth hour onward 

 (Fig. 309). Although at 60 hours not yet apparent, at 65 the proc- 

 todaeum shows the six longitudinal folds so characteristic in many groups 



