COLLEMBOLA 229 



.AnMncfaman/zma occurs abundantly on the seashore chiefly between 

 tide marks; several important embryological and anatomical mono- 

 graphs have been published regarding this species. Podura aquattca 

 is one of the most abundant members of the CoUembola; it occiu^s 

 on the surface of standing water on the margins of ponds and streams. 

 Family Entomobryid^. — This is the largest family of the CoUem- 

 bola, containing many genera and species. In some genera the 

 body is clothed with scales. To this family belongs the genus 

 Orchesella, the only genus in the CoUembola in which the antennas 

 consist of six segments. 



SUBORDER SYMPHYPLEONA* 



In this suborder the body is shortened; the last two abdominal 

 segments are quite distinct but the other body segments are fused 

 into a globular mass in which the seg- 

 mentation is more or less obliterated 

 (Fig. 236). The heart is furnished with 

 only two pairs of ostia. Tracheae are 

 present in the typical genus, Sminthnrus. 

 The external openings of the tracheee are 

 one on each side of the neck, in a vertical 

 fold; spiracles properly speaking are not 

 present (Willem '00). 



This suborder includes a single family, ^if- /36.— Pa^mwi fuscus- 

 the Sminthuridce. ^^^'^^ Lubbock.) 



Family Sminthurid^. — The principal genera of this subfamily 

 are Sfninthiirus, Paptrius, and Neelus. Each of these genera is made 

 the type of a separate family in some classifications of the order. 

 These genera can be separated as follows : 



A. Last segment of the antenrice long and divided into subsegments.SMlNTHURUS 

 AA. Last segment of the antennae short, not divided into subsegments. 

 B. Thorax shorter than the abdomen; eversible sacs of the collophore long. 



Papirius 



BB. Thorax longer than the abdomen; eversible sacs of the collophore short . 

 Neelus 



In Sminthurus, tracheee are present; in the other genera they are 

 absent or extremely vestigial. The presence of tracheas in Sminthurus 

 enables these insects to live in drier situations than can other Col- 

 lembola. The "garden-flea" Sminthurus hortensis is found upon the 

 leaves of young cabbage, turnip, cucimiber, and various other plants. 



*Symphypleona; symphyo, to grow together; pleon, a crustacean's ab- 

 domen. 



