EPHEMERIDiE. 



[ 236 ] 



EPIDERMIS. 



Body long, slender, and soft ; head small, 

 transverse-trigonate, eyes large, nearly oval. 



Fig. 202. 



Ephemera Swammerdamii. Nat. size. 



lateral; ocelli three, forming a triangle 

 between the eyes; antennae three-jointed, 

 the two basal joints thick, the third forming 

 a long slender seta. Abdomen consisting of 

 nine joints ; the terminal the longest, and 

 gradually narrowed and furnished at the apex 

 in both sexes with two or three long, slender, 

 many-jointed filaments. Legs slender; an- 

 terior pair in the males porrected, much 

 elongated, with the tibiae and tarsi appearing 

 soldered together; basal tarsal joint very 

 minute, tarsi five-jointed, terminated in the 

 forelegs of the male by two oval pul villi ; in 

 the four posterior legs tarsi short, five-jointed, 

 and terminated by a large oval pulvillus, and 

 a single broad notched claw\ 



These insects must have been seen by 

 every one, rising and falling on the wing, 

 near the banks of rivers and pools ; in the 

 perfect state, their life lasts but a few hours, 

 whence the name. The ova are deposited 

 in the water. The larva bears a considerable 

 resemblance to the pupa, from which it 

 differs in the absence of rudimentary wing 

 covers; they are frequently mistaken for 

 each other. 



The pupa of the common Ephemera {vul- 

 gata) (PI. 28. -fig. 15) has the prothorax as 

 broad as the head, transverse-quadrate ; the 

 mesothorax gibbous ; the head rather small, 

 with two short horns in front, and two horny 

 toothed mandibles, furnished at their upper 

 angles with a long curved horn ; labrum 

 flat, membranous, ciliated, and with the 

 angles rounded; maxillae small, membra- 

 nous, curved, pointed at the tip, and inter- 

 nally setose; maxillary palpi four-jointed, 

 and not extending beyond the front of the 

 head; labium large, membranous, four-lobed, 

 and furnished with a broad tongue ; labial 

 palpi broad and three-jointed; antennae 

 about twice the length of the head, many- 

 jointed and ciliated ; legs short, broad, and 

 much cora])ressed ; tarsi two-jointed, with a 

 terminal hook; abdomen nine-jointed, the 



six basal segments being furnished on each 

 side with a pair of elongated, rather narrow 

 gills or branchial plates (a), 

 with long, narrow filaments at 

 their edges, through each of 

 which a trachea extends to the 

 tip ; the tracheae from each con- 

 tiguous pair of filaments uniting 

 near the base, and then running 

 to the large tube which traverses 

 the centre of each plate ; there 

 are in all twenty-four branchial 

 plates. At the end of the abdo- 

 men are three elegantly feathery setae. 



The larvae and pupae of the Ephemeridae 

 may be most easily caught in the ring-net; 

 they are perhaps best preserved in glycerine, 

 or solution of chloride of calcium. 



BiBL. Westwood, Introduction, ^c. ; 

 Pictet, Hist. nat. d. Ins. Neuropt., 2nd 

 monogr.fam. d. Ephem. 1843 ; Curtis, Brit. 

 Entom. 708. 



EPHEMERUM, Hampe.— A genus of 

 Ephemereae (Acrocarpous Mosses), including 

 part of Phascum of authors. 



1. Ephemerum serratum, Hmp. =: PAas- 

 eum serratum, Schreb. 



2. Eph. crassinervium, C. Miill. = Ph. 

 crassinervium, Schwiigr. 



3. Ejjh. patens, Ump.^Ph. patens,H.edw. 

 EPHIPPIA.— The winter-ova of the En- 



tomostraca. See Eggs and Entomos- 



TRACA. 



BiBL. Baird, Brit. Entomostr. p. 84. 



EPIBLEMA. See the Epidermis, of 

 Plants. 



EPICOCCUM, Lk.— A genus of Stilbacei 

 (Hyphomycetous Fungi), parasitic upon dead 

 leaves, &c., consisting of very minute, grega- 

 rious tubercles, somewhat linearly arranged, 

 reddish or purplish, containing numerous 

 spherical, smooth or roughish, reticulate 

 spores. E. neglectum is adnate to a short 

 pedicel. When mature the stroma is quite 

 covered with spores about 1-2000" in dia- 

 meter. Uredo Equiseti, Br. Flora, is an 

 Epicoccum with smooth spores. 



BiBL. Desmaz. A7in. des Sc. nat. 2 ser. 

 xvii. p. 95; Berk, and Broome, Jnn. Nat. 

 Hist. 2 ser. v. p. 466; Fries, Summa Veg. 

 p. 476. 



EPIDERMIS, OF Animals. See Skin. 



EPIDERMIS, OF Plants.— There are 

 few parts of the structure of vegetables that 

 have given rise to more discussion than the 

 epidermal cells and the tissue they constitute. 

 Even the term epidermis has become to a 

 certain extent equivocal, since it is used by 



