NORTH AMERICAN APTERYGOGENEA. 171 



"to the delineation of the animal, and by disregarding the 

 difference that appears in the structure of the mucrones. 

 These bear a great resemblance to those of S. quadrili- 

 neaius Tullb., from which, however, they differ in being 

 flattened from the sides, and apparently serrulated. S . 

 niger Lbk. has the mucro distinctly in the form of a 

 channel, and serrated in both the margins. 



Gen. II. Papirius Lubbock. 



Of this genus I have in my materials also one individual, 

 which has been found in Mexico by Dr. G. Eisen. On 

 this single specimen I dare not, however, form a new 

 species. 



On a dirty white ground color there is on the back a 

 large black spot with regular outlines. 



Family ENTOMOBRYID^E Schott. 



When, a few years ago, I was occupied with Collembola 

 from California, I found a form, belonging to the family 

 Entomobryidae, which differed from all the others by the 

 falcated mucronal segment. Until further I referred the 

 form to a new genus Drepanara. Afterwards I have had 

 an opportunity to study collections from Italy, Africa and 

 America. In all of them I have found forms, among 

 other characteristics also presenting the above mentioned. 

 By the segmentation of the body they are all connected 

 with the type of JLepidocyrtus Bourl., or Entomobrya 

 Rond. 



I therefore think that the greatest order is attained 

 when (1) to the gen. JLepidocyrtus Bourl., all the forms 

 are referred which have the mesonotum more or less 

 projecting and the body clothed with scales, (2) to the 

 gen. Entomobrya Rond., forms with the mesonotum not 

 projecting and without scales, and finally (3) to the gen. 



