488 CALIFORNIA ACADEMY OF SCIENCES. 



apical half, directed upwards, the pointed black apex 

 reaching as far as the apical margin of the tooth of the 

 superiors. 



Wings clear. Pterostigma brown, rhomboidal, sur- 

 mounting a little less than one cell. Front wings with 

 8-10 postcubitals, 3 discoidal cells, nodal sector rising 

 from between fourth and fifth postcubitals to between 

 fifth and sixth. Hind wings with 7-9 postcubitals, 3 dis- 

 coidal cells, nodal sector arising at the fourth, or between 

 the fourth and fifth postcubitals. 



Abdomen 23-26. Hind wing 16-18. ? unknown. 



An interesting peculiarity is the variation in the extent 

 of the black marking on the second abdominal segment, 

 both extremes of which, and some intermediate forms, 

 are to be found in the specimens from Baja Puris- 

 ima. The grouping employed by Baron de Selys for 

 the species of Enallagiua " black spot of the second seg- 

 ment in form of an [apical] T " and " black spot of the 

 second segment a dorsal band," is therefore no longer 

 so decisive. In addition to the form of the appendages, 

 a specific character is to be found in the presence of the 

 lanceolate, basal, black spot on 3-6. 



This species is named after Dr. Gustav Eisen, the well- 

 known student of Oligoch^tous worms, to whose labors 

 so much of the present paper is due. Mr. Samuel Hen- 

 shaw has compared a male of this species with the 

 Enallagmas in the Museum of Comparative Zoology at 

 Cambridge, Mass. (Dr. Hagen's collection), and writes 

 that this species is " not in the collection." 



