Sept., '03] ENTOMOLOGICAL NEWS. 219 



authority as Mr. McLachlan). Besides a notable difference 

 in facies, there is a slight but constant neural character, 

 whereby the two groups can be separated. Old World Tri- 

 the77iis have constantly two rows of cells between the subnodal 

 and supplementary sectors ; a single row of cells in this area 

 is as constant in American Tritheniis. Only we have then to 

 remove umbrata and fimerea from the American genus ; they 

 have two rows of cells, but their nodal sector is distinctly 

 waved, whereby they are separated fron: American as well as 

 from Old World Trithemis. So we have : 



Nodal sector waved— two rows of cells between subn. and suppl. s 



umbrata and iunerea. 



Nodal sector straight— two rows id Old World Trithemis. 



one row id American Trithemis. 



Provisionally the accepted name of Trithemis may still 

 unite the three groups, but generic names must be bestowed on 

 them, when an attempt is made to bring better light into these 

 numerous and sometimes difficult tropical forms. 



21. Mesotheinis simplicicollis . Very abundant, the most 

 numerous of the Libellulinae ; many of them alighted on the 

 steamer in Chesapeake Bay when still far away from land. 



22. Pachydiplax longipe7inis . Nearly as common as the last 

 species but more confined to swampy grounds. 



The prevalence of Lib. auripe^tnis, Mesoth. simplicicollis, 

 Pachyd. lo7igipe7inis . A7iomalagr. hastatum, as well as the pres- 

 ence of PaTitala flavesce7ts , Trith. bere7iice and E7iall. durum, 

 give the Locust Point faunula a decidedly southern aspect. 

 Moreover, for a European observer, the great abundance of 

 minuscule forms — represented by /. verticalis, A. hastatum. 

 N. posita — was a most striking feature ; it reminded me of the 

 aspect of tropical swamps in India with their great abundance 

 of the minute Agrioc7iemis i7icisa, or at Bahia with Ceratura 

 capreola. 



[It is appropriate to add here the following list of captures 

 made near Chester town, Kent County, Maryland, on the oppo- 

 site side of Chesapeake Bay, between August 13 and 23, 1899, 

 by Mr. E. G. Vanatta, of the Academy of Natural Sciences 



