from the Rio Nautla^ State of Vera Cruz. 289 



present known. This is particularly the case wlien collect- 

 ing is done every day for a considerable length of time, and 

 done closely. From June 18 to July 20 I collected daily all 

 the Diptera possible, especial attention being given to the 

 Cordia flowers. It has been thought that, in the tropics 

 especially, dates are of little or no consequence; but I ob- 

 served at San Rafael, during my close collecting daily from 

 early spring to midsummer, that as the season advanced very 

 many species of insects appeared suddenly, where before 

 there had been none at all to be found. This shows that 

 species have their seasons in the tropics as well as in colder 

 latitudes, a fact wiiich is evident enough to anyone who has 

 collected carefully for any length of time in tropical regions. 



Hippoboscidae. 



LiPOPTENA. 



Since the time when, in 1823, more than seventy years 

 ago. Say described Lipoptena depressa taken from Gariacus 

 virgimanus in Pennsylvania, no mention has, to my know- 

 ledge, been made of further specimens of this genus from 

 America. It will therefore be interesting to know that I 

 secured between one and two hundred specimens from a 

 Mexican white-tailed deer near Paso de Teluya. 



45. Lipoptena depressa, var. mexicana, var. n. 



Numerous specimens of both sexes, 153 in all, together 

 with puparia, taken from ventral region, hind quarters, and 

 sides of a white-tailed deer, Cariacus virgimanus^ var. 

 viexicanus, March 27. Paso de Telaya. 



The specimens agree fairly well with Say's description of 

 depressa. The antennae are yellowish. I can distinguish no 

 brown lines on hypostoma, uidess Say and Wiedemann refer 

 to the two halves of the labrum which might have been ap- 

 pressed to the under surface in their specimens, or to tlie 

 two linear spots above on each side of base of labrum. There 

 are often, doubtless normally, three soft brownish longitudi- 

 nally-elongate spots on posterior portion of tergum, the middle 

 one the largest and heaviest, and situated a little farther 

 posteriorly than the lateral ones. The middle one is often 

 heightened, and the lateral ones obscured, by the developing 

 larval case or puparium within the abdomen of the female, 

 thus giving the appearance of a single heavy dark spot. All 

 the specimens are wingless, but the wings are represented by 

 well-developed rudiments. The lateral pointed elytra-like 



