374 gundlach's work on the odonata of cuba 



States. . Under E. pollutum, following, perhaps, my identifica- 

 tion of this species in these Transactions,^^ American authors 

 have included at least three species. One of these, the best 

 known, is that found from Maine, Ontario, and Wisconsin to 

 Florida and Oklahoma; it is not the true pollutum but distinct 

 and ma}^ be termed Enallagma vesperum. The true pollutum 

 I know from Florida only. For a third form, likewise seen from 

 Florida alone, I suggest the name Enallagma laurenti. 



Of the six species thus resulting, I know both sexes of four, the 

 males only of truncatum and laurenti. These six species agree in 

 having (in the sexes thus far known) : 



& 9 . Dorsum of abdominal segment two black from end to 

 end. 



Right and left pale postocular spots connected with each other 

 across the occiput. 



Mesostigmal lamina (caudal mesostigmal plate of Grarman, 

 1917) erect and more or less {truncatum) produced at its mesal 

 end into a tubercle. In the males the lamina does not reach to 

 the mesinfraepisternum, owing to the ventral mesostigmal plate 

 (of Garman) meeting the mesepisternum (supraepisternum of 

 Garman) ; in the females the lamina reaches to the mesinfraepis- 

 ternum and the ventral mesostigmal plate does not meet the 

 supraepisternum. 



First antennal joint anteriorly for its entire length and all of 

 the second joint, except the distal end, pale colored. 



Legs pale colored, dark markings, when present, narrow lines 

 often interrupted. 



cf . Dorsum of abdominal segment nine (but not of eight) pale 

 blue or orange (black in pictum). Superior abdominal appendages 

 not deeply bifid. 



9 . Middle prothoracic lobe with a pair of dorsal pits. 

 Dorsum of abdominal segment ten pale-colored (black in pictum) . 



The pair of dorsal pits on the middle prothoracic lobe of these 

 females does not appear to have been noticed by previous writers. 

 Each pit is oval or elliptical in outline, its greatest diameter being 

 subtransverse to the long axis of the body (plate XXXIII, figs. 5 

 and 7) . The shortest diameter, as far as measured, varies from .07 

 mm. in pollutum to .2 mm. in signatum, and varies also in the same 

 species. Thus, in signatum it ranges from .1 to .2 mm. in three 



^ XX, 239, 1893. 



