ANURIDA. 421 



Neanura, or is wanting altogether, as in Anurida, 

 and Anuropliorus. 



Many species also retain a pair of appendages on the 

 third segment of the abdomen. These resemble the 

 springing organ in their general form, but are very much 

 smaller in size. Similar to the spring, they consist of 

 a basal piece, which carries two arms ; the former is 

 termed by Tullberg the corpus (ep. in text-fig. 2), and the 

 two latter the rami (r.). This organ is usually known as 

 the " catch, 5 ' or hamula, and it is believed to serve to 

 retain the spring in position when the latter is stowed 

 away under the abdomen while not in use. The manu- 

 brium of the springing organ is retained between the two 

 rami of the " catch." 



A variable number of eyes are generaly present on 

 either side of the head behind the antennae ; their number 

 may vary even among different species of the same genus. 

 In Templetonia there is but a single eye on each side ; in 

 Anura muscorum there are three ; in Xenylla and Anurida 

 maritima there are five ; in Tomocerus and Orchesella six ; 

 while in Achorutes they reach the maximum number, viz., 

 eight. In some Collembola they are absent, as in 

 Lipura, Beckia and Anurida granaria. 



The post-antennal organ assumes a great variety of 

 forms among various genera. In Isotoma and Anuro- 

 phorus it is simple and ring-like, but in Lipura and 

 Anura it attains considerable complexity of structure. 

 In some few forms (i.e., Lipura) there may be present 

 curious structures, known as pseud-ocelli or puncta 

 ocelliformia. They are situated in front of the post- 

 antennal organ, and between it and tjie antenna ; they 

 appear to have nothing to do with eyes, and their 

 function is unknown. In certain species of Aphorura 

 they have a much wider distribution over the body. 



