PSYCHE. 



DESCRIPTIONS OF SPECIES OF MACHILIS AND SEIRA 

 FROM MEXICO. 



BY JUSTUS WATSON FOLSOM, CAMBRIDGE, MASS. 



I wish to describe Alachilis conjiincta 

 and Seira tnexicana, two new species 

 of Thysanura which were collected for 

 me in Mexico, during the suinmer of 

 1S97, by my friend, Mr. O. W. Barrett, 

 of Clarendon, Vt. 



Alachilis coitjuncta was taken in 

 September at Cuernavaca, Morelos, on 

 the Pacific slope, at an elevation of 

 5000 ft. and Mr. Barrett believes he has 

 also seen the same species in lower 

 Vera Cruz. The species is unfortu- 

 nately described from a single specimen 

 but can probably be identified without 

 difficulty. The scales from the same 

 individual are exceedingly variable in 

 form, size, number of longitudinal ribs, 

 etc., and consequently appear to have 

 very little specific value In this case, at 

 least ; the forms which I have figured 

 (Figs. 4, 5 and 6) are, perhaps, as 

 coinmon as any. The scale shown in 

 Fig. 6 deserves special mention on ac- 

 count of the obliquity and bifurcation of 

 its principal ribs ; in these respects it 

 departs widely from the type of scale 

 which prevails in the genus Machilis. 

 Seira mexica?ia occurred in abun- 

 dance near the city of Mexico, at 7300 



ft. elevation ; the species was found 

 July 9 and 13, upon grasses, and num- 

 erous examples were also taken upon 

 old cocoons on Salix Hitmboldtia?ta. 

 S. mexicana is nearest related to 

 Drepanu7-a califortiica Schott.* In 

 conformity with the wish of this author, 

 however, the genus Drepanura had 

 better be merged into Sira Lubb. " I 

 therefore think that the greatest order 

 is attained when (i) to the gen. Lepi- 

 docyrtus Bourl., all the forms are re- 

 ferred which have the mesonotum more 

 or less projecting and the body clothed 

 with scales, (3) to the gen. Entomobrya 

 Rond., forms with the mesonotum not 

 projecting and without scales, and finally 

 (3) to the gen. Sira Lbk. forms clothed 

 with scales but with the mesonotum 

 not projecting. In consequence of this, 

 the two temporary genera Drepanura 

 and Pseudosira, before proposed by me, 

 are to be excluded from the system." f 

 S. 7?iexicana difli?rs from 5". califor- 

 tiica in the plan of coloration and by 



* Schott, Beitrage zur Kenntniss KaWornischer Collem- 

 bola. Bihang K. Sven. Vet. Akad. Handlingar. Ed. 17, 

 Afd. iv, 1891. (See pp. 19—21 and Taf. iv, Figs. 2, 3 and 5) 



t Schott, H. North American Apterygogenea, Proc 

 Cal. Acad. Sc, Ser. 2, Vol. vi. 1S96. (See pp. 171—172) 



