820 AETHEOPODA phylum vii 



Order 2. CAMPODEOIDBA Handlirsch {Jrchinseda Haeckel). 



Small Apterygote entotroplious Insects {month parts or tropin reduced and buried in 

 the head), with feebly-developed eyes and long, simple, muUiarticulate antennae. Body 

 segments very nearly equal ; ten well-developed abdorainal segments, most of them with 

 reduced styliform legs ; cerci elongate or chelate. 



The so-called abdorainal legs in this grouj) and in the Tliysannia are appendages 

 which help to support the abdomen, and serve also as tactile organs. They are 

 called by Grassi false legs or " Pseudozampe." The Eecent genus Campodea Westwood 

 occurs also in Baltic amber of Lower Oligocene age. 



Order 3. COLLEMBOLA Lubbock. (Spring-tails). 



Trophi reduced and buried in the head, eyes feebly developed, antennae sometimes 

 uneq'ually segmented. Thorax with very -unecpial segments but ivith homonomous legs. 

 Abdomen consisting of not more than six segments, the first of rchich is furnished with a 

 ventral tube or papilla, and modified legs forming a springing apparatus being present 

 posteriorly. 



About 450 Eecent s^Decies of Spring-tails are known, and 70 have been recorded 

 from Baltic amber of Lower Oligocene age. The crustacean characters which we 

 tind to-daj^ in the Collembola, the Thysannra, and the Ephemerida, are, as pointed 

 out by G. H. Carpenter, without doubt inherited survivals, indicating a true relation- 

 ship Ijctween the two subphyla of Branchiata and Insecta. 



Order 4. PROTURA Silvestri (Myrientoma Berlese). 

 Minute subterraneous Insects without antennae and eyes. 

 This order is without known rejjresentatives in the fossil state. 



Geological Range and Distribution of Insecta. 



It is estimated that about 1000 Paleozoic, as many Mesozoic, and upwards of 

 8000 Cenozoic Insects have been described by different authors. The total is, 

 however, a mere fragment of the insect fauna of past periods, and very small in 

 comparison with the half million species now in existence. 



The earliest fossil Insects which have been definitely recognised are members of 

 the Palaeodictyoptera. Their first appearance in Europe is at the base of the Upper 

 Productive Coal Measures (Ouralien or Stephanien superieure of Coinmentry, France, 

 and the corresponding '• unteres Obercarbon " of German geologists). From the 

 Upper Coal Measures of France, Germany, Belgium, Bohemia, and other localities in 

 EurojDe, and froiu the Lower Productive Coal Measures (Kanawha and Allegheny 

 formations) of Pennsylvania, Illinois and elsewhere in the United States and Canada 

 has been obtained a large number of higlily interesting types.^ Other representatives 



^ The Little Kiver Group of St. Joliu, New Brunswick, whicli has yielded a number of insect 

 remains, was formerly regarded as of Devonian age, but is now assigned on the evidence of 

 Paleoliotany to the Lower Productive Coal Measures, corresponding to the Kanawha Group (upper 

 division of tlie Pottsville). A supposed insect wing, described by Moberg under the name of 

 Protocimex sibiricus, from the Graptolite beds of Sweden is probably not of Arthropod nature. 

 Another doubtful fragment, the so-called Palaeoblattina dourillei of Brongniavt, from the 

 Mesosilurian of Calvados, is interpreted by Agnus as part of the pleural lobe of a Trilobite. 

 Suggestive traces have been found in Devonian rocks of the south-east of Ireland, but no indubitalile 

 indications of Insects prior to the Carboniferous have been as yet forthcoming. The insect remains 

 found at Fairplay, Colorado, are now thought to be of Permian insteail of Triassic age. Those 

 from the Florissant lake beds are now referred to the Miocene, instead of to the Oligocene, as 

 formerly. 



