62 



clearly indicated about the stage represented in fig. 72. 

 At the time of its first appearance, the post-antennal 

 organ consists of an irregular group of cuticular 

 elevations. In the newly-hatched animal the latter have 

 decreased in number and arranged themselves in a 

 circular form, and before the permanent form is attained 

 the organ undergoes further changes and development 

 [vide Laboulbene (2)]. 



The recently-hatched insect is perfectly white, except 

 for the eyes, which are enveloped in a patch of dark 

 pigment on either side.* Except in size and colouration, 

 the young animal does not differ from the adult. The 

 pigmentation of the integument i§ acquired after exposure 

 to daylight, but it is some time before it is developed to its 

 fullest intensity. After several moults the full growth of 

 the animal is attained. 



YI.— GENERAL REMARKS ON THE 

 COLLEMBOLA. 



The general characteristics of the Collembola have 

 already been noticed (Introduction, p. 4). About four 

 hundred species have been described up to the present, 

 most of which are very small in size, and but few forms 

 attain a length greater than 5 mm. The Collembola are 

 divided into three families, and these are classified by 

 Borner (48) under two sub-orders, as follows: — 



Sub-Order I. — Arthropleona. 



Body linear and sub-cylindrical, the limits between 

 each of the segments of the abdomen distinctly indicated. 

 Vesicles of the ventral tube short and sac-like. 



* Folsom remarks that if the eggs be exposed to sunlight the 

 embryos become blackish blue before hatching. 



