400 



FSiCBE. 



[October, 1902 



Others they are spoon-shaped. In L. 

 viiltur the tip of each is formed of three 

 plates set at right angles to one another. 



The penis (Figs. 6, 7 and \\,pen.^ is 

 a chitinous tube terminating in three 

 slender prongs. Apparently the seminal 

 passage divides into three tubes at the 

 bases of these and opens by three ap- 

 ertures at their tips. The penis (Fig. 6) 

 is carried on an elevated support (Fig. 7) 

 on the floor of the genital chamber. The 

 three terminal prongs project posteriorly 

 from the latter over the tenth segment. 

 Attached to the interior of the support 

 is a large muscle apodeme (Fig. 1 1, <?/.). 



On account of the inverted position of 

 the ninth segment, the tenth segment 

 (X) comes to lie below the mouth of the 

 genital chamber instead of, as normally, 

 above it. It is composed of the ordinary 

 characteristic parts. There is a divided 

 suranal plate (so) lying here bcloiv 

 the anus, and two elongated podical 

 plates {pO({) lying above the anus. 



The eighth segment is partially rudi- 

 mentary. It consists of a narrow curved 

 bar forming the dorsal and lateral parts 

 (Figs. 3 and 10, VIII j) , and of a small 

 plate (Figs, i, 3, 4 and 10, VIII t) ap- 

 plied to the right lower aspect of the 

 base of the hypopygium. The eighth 

 segment is symmetrical in shape but 

 asymmetrical in position. Normally it 

 is almost hidden within the seventh 

 segment (Fig. i). 



The rectum lies in the right side of 

 the body cavity of the hypopygium, turn- 



ing in mesially at the base of the tenth 

 or anal segment. Hence, the hypopyg- 

 ium must have revolved to the right 

 from above. If this is so, then the 

 small dextro-ventral plate of the eighth 

 segment is probably the eighth tergum 

 which has revolved through only about 

 150°. The seventh segment is normal, 

 the revolution having taken place en- 

 tirely back of it. It is small and is 

 mostly concealed within the sixth 

 segment. 



Explanation of Plate . 



Fig. I, Dasy/tis grossa, lateral view of 

 hypopygium ; Fig. 2, D. grossa, dorsal 

 view of hypopygium ; Fig. 3, D. grossa, 

 eighth segment ; Fig. 4, D. grossa, ven- 

 tral view of hypopygium ; Fig. 5, D. 

 postieata, interior view of right half of 

 ninth sternum, showing attachments of 

 appendages (zand l> ; Fig. 6, D. postieata, 

 dorsal view of penis; P"ig. 7, D. grossa, 

 lateral view of ninth tergum and penis, 

 and tenth segment ; Fig. 8, D. grossa, 

 appendages l> ; Fig. 9, D. grossa, ap- 

 pendage a ; Fig. i o, D. flavicollis, lateral 

 view of hypopygium; Fig. 11, D.flavi- 

 eollis, lateral view of penis and its sup- 

 port. VI /, VII /, VIII /, IX /, sixth to 

 ninth abdominal terga ; VI s, VII j-, 

 VIII s, IX s, sixth to ninth abdominal 

 sterna; X tenth segment; a, lateral 

 appendage of ninth sternum ; b, dorsal 

 appendages of ninth sternum; pen, 

 penis ; ap, apodeme ; sa, suranal plate ; 

 pod, podical plates. 



