SUBPHYLUM III 



INSECTA 



819 



Prothorax relatively large; legs similar, or the third jmir adapted for springing; 

 abdomen without cerci ; females often with a terehra. 



This grouj) is divided into five suborders, the most primitive of which is the 

 Auchenorhyucha, ranging from the Lias onward. It is represented in Mesozoic rocks 

 by 50 species, in the Tertiary by about 200, and in the modern fauna by upwards 

 of 10,000. Most of the Jurassic species belong to the families Fulgoridae (typified 

 by Fulgoridimn Handl.) (Fig. 1592) ; f Procercopidae (typified by Procercopis Handl.) 



Fulgoridium, pallidum Handl. Upper 

 Lias ; Dobbertin in Mecklenburg. B/i 

 (after Handl irsch). 



Fio. 1593. 



Procercopis alutacea Handl. Upper Lias ; Dobbertin in 

 Mecklenburg, -^/i (after Handlirscli). 



(Fig. 1593) ; and Jassidae. One species of Cicadidae is reported from the Cretaceous, 

 and a dozen from Tertiary strata. The Fulgoridae, Cercopidae and Jassidae are 

 represented by numerous species in the Tertiary, and are now flourishing families. 

 The suboT'ders Psylloidea and Aphidoidea have a continuous range from the Jura 

 onward, and the division of Aleurodoidea is Tertiary and Recent, but is represented 

 by relatively few species. Plant-lice (Aphididae) and Harvest-flies (Cercopidae and 

 Cicadidae) occur frequently in the Tertiaries of Utah, Wyoming, Colorado and British 

 Columbia. 



Class 2. APTERYGOGENEA Brauer (Ajytem Linnaeus).^ 



Purely ivingless Insects. Abdomen \oith from six to twelve segments. No meta- 

 morphosis. 



Order 1. THYSANURA Latreille. 



Small Apterygote Insects with orthopteroid, free mouth parts and simple multiarticu- 

 late antennae. Compound eyes present ; head ivith broad basis joined to thorax, which 

 consists of three divisions; tergite usually well developed, pleurite and sternite small; 

 prothorax as large as, or larger than the mesothorax. Abdomen consisting of ten well- 

 developed segments and bearing distinct cerci, a ter- 

 minal filum, and reduced styliform abdominal legs on 

 most of the segments. 



The families belonging to this grouj), Machilidae Fn'- 1594. 



and Lepismidae, are ectotrophous — that is, the mouth Mackilis seticomis (Koch and 

 ^ 1-1-T111 1- Berendt). Lower Ohgocene ; Baltic 



parts are not buried in the head, but are arranged in amber. •■2/1 (after Koch and Berendt). 



the fashion usual among mandibulate Insects. Both 



families are represented in Baltic amber of Lower Oligocene age, the genus Machilis 



Latr. (Fig. 1594) being specially abundant. Lepisma Linn, is represented by several 



European and one North American species in the Oligocene. 



^ Olfers, W. M., Die Ur-Insekten (Thysanura and Collembola im Bernstein), 

 physikal.-okon. Ges. Konigsberg, 1907, vol. xlviii. * 



Schrifteu <ler 



