SUBPHYLUM III 



INSECTA 



819 



Prothorax relatively large ; legs simüar, or the third imir adapted for springing ; 

 ahdomen without cerci ; females often with a terebra. 



This group is divided iiito five siiborders, tlie most primitive of wliicli is tlie 

 Auchenorliyncha, ranging froni the Lias onward. It is represented in Mesozoic rocks 

 by 50 species, in the Teitiaiy 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 Fulgoridium. Handl.) (Fig. 1592) ; f Procercopidae (typified by Procercopis Handl.) 



Fig. 1592 



Fidijoridium pallidum Handl. Upper 

 Lias ; Dobbertln in Mecklenburg, ö/j 

 (after Handlirscli). 



Fig. 1593. 



Prooercopis alutacea Handl. Upper Lias ; Dobbertin in 



Mecklenburg, ^/j (after Handlirscli). 



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

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

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

 The suborders Psylloidea and Aphidoidea have a continiious ränge from the Jura 

 onward, and the division of Aleurodoidea is Tertiary and Kecent, 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. 



Olass 2. APTERYGOGENEA Brauer (Apiera Linnaeus).i 



Piirely wingless Insects. Ahdomen with from six to twelve segments. No meta- 

 morphosis. 



Order 1. THYSANURA LatreiUe. 



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

 late antennae. Compound eyes present ; head with hroad 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 group, Machilidae Fig. 1594. 



and Lepismidae, are ectotrophous — that is, the mouth MachjHs seticornis (Koch and 



^ i-i-iiii ^ • Berendt). Lower Oligocene ; Baltic 



parts are not buried 111 the head, bat are arranged m amber. a/j (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. 



^ Ol/ers, W. M., Die Ur-Insekten (Thysanura inid Collenibola im Bernstein). Scliriften der 

 physikal.-ökou. Ges. Königsberg, 1907, vol. xlviii. ' 



