ODONATA OF BAJA CALIFORNIA. 539 



• 34. MiCRATHYRIA DIDYMA SclyS. PL xvii, figS. 98- 

 102. 



Lihellula d. Selys in Sagra's Hist. Cuba, Ins. p. 453, 1857. Dijthe- 

 mis d. Hagen, Proc. Bost. Soc. N. H. xviii, p. 75, 1875. M. d. 

 Kirby, Cat. Odon. p. 41, 1890. Lib. phryne Rambur, Ins. Nevr. 

 p. 121, 184-2. Dythemis dicrota Hag. Syn. Neur. N. A. p. 166, 

 1861; Proc. Bost. Soc. N. H. xi, p. 292, 1868. Mesothemls Poeyi 

 Scndder, Proc. Bost. Soc. N. H. x, p. 194, 1866; xi, p. 300, 1868. 

 Hagen, Stet. Ent. Zeit. xxviii, p. 98, 1867; Proc. Bost. Soc. N. 

 H. xi, p. 292, 1868; xv, p. 375, 1873. 



3 3 San Jose del Cabo, October, 1893, G. Eisen. 



1 San Jose del Cabo, not dated. 



$ Closely resembles M. Hagenii in coloring, having 

 however the green antehumeral stripe narrower, brown 

 stripe on the first lateral thoracic suture not forked, green 

 spots on abdominal segments 3-6 narrower — in fact, nar- 

 row stripes. Tip of vertex more distinctly bifid than in 

 Hagenii. Superior appendages similar, but showing a 

 tendency to form an obtuse inferior tooth at the position 

 of the last denticle. 



Distinctive characters presented by the genitalia. An- 

 terior lamina bifid to base so that when viewed in front 

 it forms a distinct and straight tubercle each side, whose 

 apex is narrower than its base and is not denticulated. 

 Hamule very peculiar, bifid; that which apparently cor- 

 responds to the external branch is greatly prolonged, 

 more prominent than any adjacent part,, curving forwards 

 and ventrally as a lamellate process with its apex extend- 

 incT below and a short distance in front of the level of the 

 anterior lamina; a short distance before its apex, this 

 process is constricted, while the apex is widened into a 

 flat plate whose apical margin is denticulated. The ap- 

 parent homologue of the internal branch of other species 

 is a small, curved, acute spine directed backwards and 

 first inwards, then outwards, and projecting ventrally a 

 little farther than the genital lobe. Genital lobe small. 



