Calvert : Odonata of the Neotropical Region. 201 



other female has the nasus and the upper surface of the head olive, with 

 blue postocular spots as above described, and the dark markings on the 

 abdominal segments are merely dull brown. Neither female has a 

 vulvar spine, but the posterior ventral margin of 8 is convex. Ab- 

 domen cT 26.5-27.5, 9 27; hind wing cJ 1 14. 5-15, 9 17 mm. 



Habitat : — Dutch Guiana, Paramaribo, by Miss Katherine Mayo, 

 2 cT, 2 $. Academy of Natural Sciences of Philadelphia. 



Specimens from Ecuador also appear referable to this species, but 

 have a greater extension of dark colors : 



c?9. Dorsum of abdominal segments 4-7 dark metallic-green, 

 except for a narrow transverse mid-dorsally interrupted basal yellow 

 ring on each and, in some at least, the hind end of 7, which is reddish. 

 The head is a little wider (3.12-3.44) than in typical vacillans from 

 Cuba and Guatemala (2.72-2.88 mm.), the examples from Para- 

 maribo being intermediate in this respect (3-3.12 mm.). One of the 

 three females has a very minute vulvar spine, the other two lack this 

 feature, but the posterior ventral margin of 8 is strongly convex in all 

 three. 



Abdomen oT 28-29, ? 27. 5—28. 5 ; hind wing $ 15-16, 9 17 mm. 



Habitat : — Ecuador, Guayaquil, 5 d\ 2 9, and Quevedo, 5 d\ 

 1 9, all by Prof. F. Campos R. Academy of Natural Sciences of 

 Philadelphia. 



If it be desirable to distinguish these forms of vacillans by sub- 

 specific names (and of this I am not yet assured), those of guiance 

 and ecuadorica may be suggested. 



106. Leptobasis mammilaris sp. nov. 



(Plate VI, figs. 112, 113, 11 5-1 17.) 



cT. Dorsum of head and of thorax reddish-yellow, the following 

 pale green or blue : genae, rear of head, antehumeral stripe (one- 

 fourth to one-fifth as wide as its mesepisternum), and a stripe on the 

 metepisternum and adjacent part of the mesepimeron ; labium, met- 

 epimera, and pectus pale yellow. 



Hind margin of prothorax trilobed, median lobe widest and most 

 prominent, rounded, but not greatly produced. 



Mesostigmal laminae well, but not excessively, developed, vertical. 

 Behind each lamina on the anterior or lower end of each mesepi- 

 sternum is a distinct rounded tubercle, situated between the fork of 



