384 gundlach's work on the odoxata of cuba 



(gjTiandromorphic) cf . Florida, Palm Beach, November 12, 1911, G. P. 

 Englehart, 1 cf (these last 2 cf in the Museum of the Brooklyn Institute of Arts 

 & Science). Oklahoma, Wister, June 3, 1907, 1 d". Total 38(f cf, 10 $ 9 , 



It is a pleasure to acknowledge the aid given by Mr. E. B. 

 Williamson and by Mr. Charles Schaeffer, of the Brooklyn Insti- 

 tute, in lending me specimens from the respective collections 

 under their care, as cited above. 



The name vesperum is suggested for this species by its habit of 

 flying after sunset to a degree greater than in most of its allies. I 

 observed this at Sawkill Pond and Black Lake in 1898, and at 

 Pemigewassett Pond, July 20, 1917, at 7.50 p. m. Prof. Need- 

 ham (1908) noted it at Walnut Lake, Michigan, as the "latest 

 flying of all Odonata," and Dr. Howe (1917) writes of it as 

 "semicrepuscular." It does not confine its flight to the evening 

 hours, however, as the River Styx male was taken in the morn- 

 ing. It is found on ponds, flying from leaf to leaf of the floating 

 vegetation. 



Larva. Dr. E. M. Walker has despribed and figured details 

 of supposed nymphs of this species, from Georgian Bay, Onta- 

 rio. ^^ Garman (1917, p. 553) had nymphs from which adults of 

 this species were reared and says: "It (the nymph) is quite dif- 

 ferent from the species figured by Walker as poUutum ('13; pi. i, 

 fig. 10), and his description also differs from the specimens ob- 

 tained at Lake Villa," Illinois. Garman gives a description of his 

 nymphs (p. 550). 



I have an exuvia from which a male vesperum emerged at 

 Pemigewassett Pond, July 15, 1917. This exuvia differs from 

 both descriptions by Walker and Garman, as indicated by the 

 following: 



Eyes not very prominent laterally, their postero-lateral margins not forming 

 a marked excavation with the sides of the head. About thirteen spinules, or 

 short setae, of varying length can be seen on the dorsal surface of each hind 

 angle of the head, these angles not nearly as prominent as in Walker's figure 9, 

 but more like those of his figures 4 or 6. Second antennal joint lotujer (.21 mm.) 

 than the first (.14 mm.); no definite difference in color. 



Two mental setae on each side, a third much smaller and more proximal, in 

 addition on the right side only; five setae on each lateral lobe, whose apical 

 margin bears, next to the movable hook, a low convex lobule with about five 



^' Can. Ent., xlv, 162, pi. i, figs. 9, 10, 1913. Reprinted in Supplement to 

 47th Ann. Rep. Dept. Marine & Fisheries, Fisheries Branch, Sessional Paper 

 39b, p. 68, pi. iii, figs, 9, 10, Ottawa, 1915. 



