554 proceedings of the academy of [aug., 



Abbreviations. 



AcSt accessory parts of sting. 



Amp ampulla of gland cell. 



AntP anterior portion of articular membrane. 



ArtM articular membrane. 



Can canal. 



CanTu canal of chitinous tube. 



Ch chitin. 



CIS clear spot in cytoplasm of cell. 



DDph dorsal diaphragm. 



ECan end of canal. 



FC fat cell. 



GIC gland cell. 



Glo globule of cell. 



Gr groovelike indentation in chitin forming canal. 



H heart. 



Hr hair. 



HrS hau- socket. 



Hyp hypodermis. 



HypC hypodermal cell. 



Lint large intestine. 



M muscle to move sting. 



Mai Malpighian tubules. 



CE oenocyte. 



PostP posterior portion of articular membrane. 



RadStr radial streak of ampulla. 



SInt small intestine. 



St sting. 



T trachea. 



Tu chitinous tubes of gland cells. 



TrA tran.sparent area in ampulla. 



VDph ventral diaphragm. 



a to / of figure 2. — a, small barbed hairs; b, small spinelike hairs; c, groovelike 

 indentations on anterior portion of articular membrane; (/, heavy and wide 

 vein of chitin between anterior and posterior portions of articular membrane; 

 e, heavy and narrow vein of chitin in posterior portion of articular mem- 

 brane; /, location of gland cells. 



a to e of figure 4. — a, comparatively thin and almost transparent chitin; b, 

 narrow, thick and yellow band of chitin; c, thick, semitransparent band 

 of chitin; (/, wide, thick and opaque band of chitin; c, thick semitransparent 

 chitin. 



a to b of figure 9. — a, hypodermal cells, which later become gland cells, now 

 broken loose from hypodermal layer; 6, a later stage of same. 



V, the heavy and wide vein of chit in shown in figure 2, d. 



Fig. 1 has been placed in the text. 

 Plate XIX. — Fig. 2. — Diagram of articular membrane spread out flat under a 

 low-power lens, showing its su])(>rficial appearance, and looking through the 

 posterior part {PudP) of meml)rane at a deejier focus may be seen gland 

 cells and tubes as shown at/. The material used for figs. 2 to 7 inclusive 

 was fre.sh and was stained slightly with a weak solution of methyliti green. 



Fig. 3. — A small portion of anterior part (AiitP) of membrane from fig. 2, 

 showing the groovelike indentations {(ir). X 700. 



Fig. 4. — A small portion of posterior part {PostP) of nuimbrane from fig. 2, 

 looking at inner side of chitin with strong transmitted light. Four gland 

 cells {GIC) and many tubes (7'm) are shown. The tubes are twice too 

 wide. X 275. 



Fig. 5. — Large live gland cell, showing its structure. 



Fig. 6. — Large live cenooyte, showing its structure. 



Fig. 7. — Small live fat cell, showing its structure. 



