442 LECTURE XIX. 



Order Nedroptera. (May-flies, Dragon-flies.) 



Four wings, membranous, veined with numerous reticulate ner- 

 vures. Larvae hexapod, unlike imago ; in many aquatic. 



Families PhryganidcB, SialidcB, Hemerohidce, Myrmeleonidce, Tev 

 mitidce, Raphidiad(S, Panorpidce, Mantispidce, Ephemeridce, Libel- 

 lulidce. 



Order Orthoptera. (Crickets, Cockroaches.) 



Four wings ; the first pair coriaceous, nerved ; second pair folded 

 fan-wise, longitudinally. Larvse like imago, save in wanting wings. 



Families Forficulidce, Psocidce, Acrididce, Achetidce, PhasmidcB, 

 Mantidce, Blattidce. 



Order Coleoptera. (Beetles.) 



Four wings ; the first pair elytra, or hard covers to the under 

 wings, which are folded transversely when so protected. Larvse ver- 

 miform, hexapod in most. 



A. Pentamera. Five joints in all the tarsi. Families Cicinde- 



lidcB, CarabidcB, Hydrocanthari, Brach- 

 elytra, Buprestidce, ElateridcB, Clavicornes, 

 Hydrophilidce, Lamellicornes. 



B. Heteromera. Five joints in the four anterior tarsi, four joints 



in the last tarsi. Families Blapsidce, Tene- 

 brionidce, Taxicornes, Cistelid(B, Meloidce. 



C. Tetramera. Four distinct joints in all the tarsi. Families 



Bhyneophoridce, Curculionidce, Xylophagi, 

 Cerambycidce, ChrysomelidcB, Coccinellidce, 

 Pselaphidce. 



LECTURE XIX. 



AR^CHNIDA. 



There remains one class of articulate animals to be considered in 

 our present ascending survey of the animal kingdom, and which, 

 therefore, you will conclude to be the highest organised of the 

 homogangliate Invertebrata. Yet the species which are grouped 

 together under the name Arachnida never acquire wings : some are 

 parasitic, many terrestrial, and a few aquatic : there are species, 

 however, that, notwithstanding their apterous condition, can rise and 

 float through the air, which they efiect in a manner analogous to 

 our aeronauts, by manufacturing, and suspending themselves to, a 

 foreign substance light enough to be buoyed up and wafted along by 

 the atmospheric currents. The animals to which I allude, and whose 



