xxxiii, '22] ENTOMOLOGICAL NEWS 37 



proximal meatns. See fig. 16, dm and pm. Williamson was 

 the first to point out that the penis had two openings. He has 

 figured these for DesmogompJms. 5 In the naiad both meat 

 face ventrad, as shown in fig. 17. At the emergence of the naiad 

 into imaginal life the penis bends at the level of the proximal 

 meatus, so that this meatus faces cephalad in the adult. The 

 distal meatus is guarded by the two medial lobes, but the 

 proximal meatus lies fully exposed on the outer bend of the 

 penis. 



In Desmogomphus, \Yilliamson uses the old terminology 

 and calls the inflated base the "vesicle." Distad to this are three 

 other joints, which he terms first, second and, third, the apical 

 segment being the "third." As the "vesicle" of the old termin- 

 ology is merely the inflated base of the penis, this becomes seg- 

 ment 1, as I have named the parts in this article, so that the 

 Desmogomphus penis has four joints where the Libcllula penis 

 has but three. The segments still homologize in the two penes. 

 Segment 4 of the Dcsnwgouiphiis penis is merely the region of 

 the distal meatus drawn out into a small apical segment not; 

 found in Libcllula. Segment 3 of the penis of Libcllnla equals 

 segments 3 and 4 of the Desmogomphus. 



The two meati are connected by a tube, which is marked T 

 in fig. 17. At either end this tube is dilated into a vesicle. The 

 distal vesicle, dv in fig. 17, lies just within the tip of segment 3. 

 The proximal vesicle, pv in fig. 17, lies exactly in the flexible 

 outer bend of the (adult) penis. In the Libcllula penis these 

 openings and vesicles do not connect with the cavity or inflated 

 base of the penis. The true seminal vesicle is this pair of 

 connected pockets in the apex of the penis and not the inflated 

 base of it, as has hitherto been supposed. Just how these apical 

 vesicles and meati function can be only surmised in our present 

 ignorance of their action. No muscles or other structures 

 insi'de the penis were found that might operate them. As the 

 proximal vesicle, p-r, lies exactly in the flexible bend of the 

 penis, its action in filling and emptying is probably directly cor- 

 related with the motions of this joint. The distal vesicle, dr. 



' A nc\v Gomphine j^mis from I'.ritish Ciuiana. Occ. Papers No. 80, 

 Mus. Zool. Univ. Mich., 1920. 



