262 THE WONDERS OF CxEOLOGY. Lect. III. 



Formation of Aix, in Provence," by Mr. Lyell, and Sir 

 R. I. Murchison.* 



All the insects belong to existing genera, and only one 

 species is aquatic, f The anterior tarsi are generally 

 obscure, or distorted ; but in some specimens the claws 

 are visible, and the sculpture, and even a degree of local 

 colouring, are preserved. The nerves of the wings in the 

 Diptera, and the pubescence on the head, are distinctly seen. 

 Several of the beetles have the wings extended beyond the 

 elytra, as if they had fallen into the water while on the wing, 

 and had made an effort to escape by flight. M. Marcel de 

 Serres has enumerated nearly seventy genera of insects, 

 and a few Arachnides, or spiders. The most curious fact 

 is, that some of the insects are identical with species which 

 now inhabit Provence. It seems probable that these insects 

 were brought together from different localities by floods, 

 and mountain streams ; yet, as Mr. Curtis observes, all of 

 them might have inhabited moist and shady forests. The 

 laminated marls contain also the coverings of the fresh- 

 water crustacean, called Cypris, which swarms in our pools 

 and stagnant waters, and must be familiar to all who have 

 seen the exhibition of the oxy-hydrogen microscope ; living 

 cyprides being commonly shown, and appearing somewhat 

 like the head and feet of a flea protruding from an oval case 

 or shield, and swimming by means of their fine cilia, which 

 resemble pencils of hair. These crustaceans shed their 

 cases annually, and the surface of the mud spread over the 

 bottoms of lakes is often covered with their relics. The 

 marls of Aix, as well as of many other fresh-water 

 formations, abound in fossil Cyprides, which oftentimes 

 constitute entire seams or thin layers. 



The seed-vessels of the Chara, a common plant in our 

 ditches and ponds, also occur in profusion ; they were 



* Jameson's Edinburgh Journal, for 1829. 

 f Principles of Geology, vol. iii. p. 211. 



