No. 2. — The Anatomy and Physiology of the Mouth-Parts of 

 the Collembolan, Orchesella cincta L. 1 By Justus Watson 

 Folsom. 



INTRODUCTION. 



The group Apterygogeuea (Apterygota) of Brauer comprises two 

 distinct groups, termed the orders Collembola (Lubbock) and Thysanura 

 (Latreille). The Collembola, to which Orchesella belongs, have been 

 comparatively little studied by naturalists, owing in part, no doubt, to 

 their being small, unobtrusive, and delicate insects. It is not surprising, 

 in view of the small size of the Collembola, that entomologists have 

 described their mouth-parts imperfectly and very diversely ; on the other 

 hand, it is remarkable that so much good work has already been accom- 

 plished by dissection, unaided by the improved modern methods of 

 technique. 



An excellent resume of preceding descriptions of the mouth-parts has 

 been given by Lubbock ('73), to whose account, however, I shall make 

 certain additions. 



Fabricius (1777) briefly mentions the palpi, mandibles, maxilla?, and 

 bifid labium of Podura, the genus in which all Collembola were origi- 

 nally placed. His description, especially inapplicable as regards the 

 palpi, has been commented upon by Latreille and Lubbock. 



Latreille ('32), who noticed the labrum, was hardly more successful 

 than his predecessor. His account, quoted in full by Lubbock ('73), is 

 characterized by the latter as being "vague as well as inaccurate." 



Bourlet ('39), in a brief paragraph, also quoted by Lubbock ('73), 

 adds " une languette large, saillante, ciliee, a deux divisions, chaque 

 division quadrifide." Like Fabricius, he erroneously supposed that there 

 were two pairs of palpi, to which he gave names. 



Nicolet ('41), in his classical memoir, gives an extended and careful 

 description of the most salient characteristics of the mouth-parts, recog- 



1 Contributions from the Zoological Laboratory of the Museum of Comparative 

 Zoology at Harvard College, under the Direction of E. L. Mark, No. XCVI. 

 vol. xxxv. — No. 2. 1 



