34 ENTOMOLOGICAL NEWS [Feb., '22 



these have attempted to cover too much ground, as the penis is 

 very different from genus to genus. 



Studies of the developing naiad 3 indicate that the penis in 

 the Anisoptera is an outgrowth of the anterior end of the 

 sternum of abdominal segment 3. It is flask-shaped. The 

 inflated base attached to the sternum, represents the body of 

 the flask, while the shaft and many lobed tip represent the 

 neck of the flask. See Plate II, fig. 4, which is the penis of 

 Libcllnla composita. The Libcllnla penis is divided into three 

 segments by two flexible joints. Segment 1 is the inflated base, 

 segment 2 the short shaft, which bears a short spur on its dor- 

 sal apical end, while segment 3 is the distal portion, which con- 

 tains the seminal vesicles and meati and which bears at its 

 apex an assortment of lobes. In the Libellulinae the apex of 

 the penis may bear as many as nine lobes, which are so modified 

 from genus to genus that it is difficult in some instances to fig- 

 ure out their homologies. The first half of this article will 

 concern itself largely with these lobes. 



THE EXTERNAL ANATOMY of the penis has been discussed 

 by Miss Goddard, by Schmidt and by Bartenef. Schmidt did 

 not name the parts. Miss Goddard named them but Bartenef 's 

 terms, 4 though later, are so much more apt that they have been 

 followed in this paper. The latter author used the penis in his 

 monographic revision of the genus Sympetrum, so the present 

 writer has begun this study by showing how Bartenef 's terms 

 apply to the penis of our own Sympctrmn scniicinctum. See 

 Plate II, figs. 1 and 2. In this species all the lobes are about 

 equally developed, which may be a primitive character. The 

 only species of Libcllnla in which a similar condition exists is 

 semifasciata on account of which condition the writer has con- 

 sidered scmifasciata to be our most ancient Libcllnla. The 

 individual lobes' will be discussed as follows: 



Lateral lobes (marked L in all the figures). These are the outer and 

 most conspicuous pair of lobes and are usually heavily chitinized. In 

 Sympetrum scmicinctum, Plate II, figs. 1 and 2, they are flattened 

 cylinders as also in Libcllula angclina, Plate II, fig. 7. In semifasciata 



3 Thompson, Backhoff. 



4 Bartenef. Fig. 9, p. 24, Libellulidae, Ins. Neur. Faune Russe. 



