EXPERIMENT STATION BULLETIN. 



responding accessory glands. These two glands empty ventrally, on 

 the median plane, into the ejaculatory duct, which passes at once 

 dorsally to the left and forward in a broad arch to where it joins the 

 anterior end of the resting penis. Snodgrass has given, also, at "E" 

 in his Fig. 50 (reference) an excellent side view of the resting invagi- 

 nated copulatoiy organ showing its basal pouches (marked "ZZ" in his 

 figure) unfolded and lifted up. This organ, as well as the ejaculatory 

 duct, is essentially a chitinous tube surrounded by its layer of hypo- 

 dermal cells. Externally, the tube opens by a wide crumpled slit on the 

 median line far toward the posterior ventral side of the drone's abdo- 

 men. In the resting condition the genital filit is entirely hidden by the 

 fused triangular plates bounding it on the anterior ventral side and 

 by the dorsal gciiito-anal cover plate. A-t the extreme posterior end 

 (just anterior to the external slit) the penis wall is very thin and from 

 its sides arise the large membranous pouches or pncninoiilnj.'^-es (zz) 

 already mentioned. Attached about the wrinkled base of the penis 

 even up to the origin of the pneumoi)hyses are many small tracheae the 

 special significance of which will appear later. These tracheae may 

 easily be seen under the binocular microscope in a properlv prepared 

 dissection of the drone's abdomen. Likewise, such a dissection, uv refer- 

 ence to Snodgrass' drawing or to Plate I of this bulletin, will show 

 how singularly the wall of the copulatory tube is differentiated in the 

 remainder of its length both as to shape and chitin structure. On 

 the ventral wall just anterior to the bases of the pneumojihyses is an 

 oblong, somewhat quadrangular, thick chitinous plate (Fig. :{, xx). 

 Immediately anterior to this plate is a series composed of three narrow 

 cross-striped rliitiiioiis ridf/es and four more weakly chitinized ones 

 with corresponding creases— the whole set appearing, at first sight, 

 somewhat as a broken or interrupted spiral band ( vv. Fig. :',). On the 

 dorsal wall opposite the anterior end of the ventral cpnidraiK/tilar plate 

 is a triamjalar plate of chitin {ww) having its broadest or basal portion 

 directed backward. Both of the plates and the stronger cross-striped 

 chitm ridges are clothed with spinules or hairs inside the resting tube 

 The extreme forward end of the copulation tube is greatlv enlarged 

 ^f\^V^^-^^&V^<^ inlb (B, Fig. 3) which goes over in the ejaculatory 

 duct (EjD) at Its anterior point. In the dorsal wall of the bulb is a 

 pair of .ymmetriral chitinous plates (tt) one lying on either side of 

 the median Ime. They are widest at their anterior ends and taper to 

 slender, parallel prongs (P) at the posterior ends. Also each plate 

 bears posteriorly by a thin arm a little ehitin-icing (wc) on the cor- 

 ""Tlf't^ T^'u'* ^'^^ ^™^^- ^^'^ hypodermis of almost the whole dorsal 

 ot nnlv tn If' P'"'""/- ^ •^''"''^^ longitudinal fold, which gives rise 

 Scribed \ut ^^f^«/r"^f™al plates and little chitin wings already de- 

 touS iel finn , II ^'^' :'"'''" thickening (named by Snodgrass) of 

 cross sfctlnnfi con^^^tency. This elastic thickening is shown in 

 r All tt fif ""''"'T'' ""^ "•'^"' "> ^'^- » ^°'^ i" siJrface view Fig. 

 ance wli e ^Tlll ^'"""'T^ '' \''' P^"^^ ^^'"" "^'^ ^^^itish in appear- 

 uiowu TO Clark brown. Finally, arising from the dorsal side nf the 

 tube immediately posterior to the bulb fs a thin . alled'L"?; p?*.J'! 



