EPHEMERIDJE. 593 



Mr. Scudder has more recently described in the "Palaeon- 

 tology of the Illinois Geological Survey," iii, p. 566, two other 

 forms of this group. He remarks, "the two specimens before 

 me, with wings better preserved than in the individual of Mia- 

 mia Bronsoni, prove that my delineation of the conjectural 

 parts of the wing structure of the Palcvopterina was in part 

 erroneous, and give evidence of a closer relationship of the 

 Palaeopterina to the ancient Termitina than I had supposed 

 possible." A second species of Miamia from Morris, Illinois, 

 he calls M. Dance (Fig. 574 ; all the specimens occurred in 

 balls of iron stone). It is four- fifths smaller than M. Bron- 

 soni. He also remarks, "the other fossil which I would refer 

 to the Palceopterina is Chrestotes lapidea (Fig. 575). The 

 genus differs from Miamia in the shortness and rotundity of 

 the wings," and in the venation, some points of which remind 

 him of the Blattarice. 



EPHEMERID.E Leach. The May-flies, or Ephemerids, as 

 their name implies, are, when fully grown, very short-lived 

 insects, the adult living but a few hours. The body is slender 

 and weak, being very long ; the prothorax is of moderate size ; 

 the antennae are subulate, or awl-like, being very small, as in 

 the Libellulidce, while the parts of the mouth are rudimen- 

 tary, the insect taking no food in the adult or imago state. 

 The wings are very unequal in size, the hinder pair being much 

 smaller, or in some instances (Cloe and Caenis) entirely 

 aborted ; the transverse veins are either few or numerous ; the 

 tarsi are four or five-jointed, and appended to the long, slender 

 abdomen are two or three long caudal filaments. 



The sexes unite while on the upper surface of the water, and 

 after a short union the female drops in the water her eggs "in 

 two long, cylindrical yellow masses, each consisting of numer- 

 ous minute eggs." Walsh states that he possesses a "sub- 

 imago of Palingenia bilineata, which oviposited in that 

 state." The larvae live in running water and prey on small 

 aquatic insects, the body being long and flat, with long hair- 

 like antennae, and small eyes situated on the side of the head, 

 the ocelli not usually being present, and long sickle-shaped 

 jaws, while along each side of the abdomen are leaf-like or 

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