♦236 W. WESCHE ON THE GENITALIA OF 



organ ; at the upper part this membrane has a number of 

 chitinous plates and two hooks adhering to its surface. This 

 structure is similar to that found on the genitalia of many 

 insects. I give figures of that of Apis melifica, Si an( i that 

 of G. palpalis for comparison, both drawn to the same scale 

 (Figs. 10 and 11). Above the adminiculum are complicated 

 pieces of mechanism, which on dissection are found to be paired 

 processes ; these are articulated on to the tops of the rods, which 

 are rounded off for that purpose (Fig. 7). The diagram and 

 drawing will better explain their shape than a lengthy descrip- 

 tion. I know of no similar structure in the Diptera, and I can 

 only suggest that they may homologise with some of the plates 

 found in Blatta, and thought to be of use in opening the genital 

 pouch of the female cockroach. 



Attached to the rods that form the penis are two chitinous 

 plates, one to each rod, which appear connected with the enclosing 

 wall of chitin (Fig. 4). This wall supports the forcipes interiores, 

 which appear to have fused with the genital palpi and to have 

 interchanged functions. On the hooks are some of the most 

 remarkable hairs I have met with in insect anatomy. I have 

 drawn a few of the extremities (Figs. 8 and 9). It can now be 

 seen that, although these parts homologise with the genitalia of 

 Scatophaga lutaria, there are striking differences. 



(1) The penis is clearly a paired organ. (2) It does not spring 

 from a sheath or from the same base as the appendages, but is 

 continued downwards until it fuses into a disc, the whole working 

 in the cavity formed by the surrounding walls. (3) Although it 

 does not spring from the same base as the appendages, yet it is 

 connected with it by two plates. (4) The chitinous wall probably 

 homologises with the sheath of the penis. (5) The forcipes 

 interiores and the palpi are fused together, and appear to have 

 interchanged functions. (6) The process on the extremity of 

 the adminiculum appears not to have been observed before in the 

 Diptera. 



