REV, A. E. EATON ON RECENT EPHEMERID.^ OR MAYFLIES. 333 



Plate XXII. 



Neuration, limbs, and external ^ genitalia of 38. Ametropus, 39. Atopojms, and 

 40. Thalerosphynis : — all enlarged. 



Pigs. 38. Am. fragUis : — fore wing and most of the hind wing; fore leg of $ adult, and of ^ adult and 

 subimago, with a more enlarged view of d' intermediate leg ; underside view of force^Ds, with a 

 part of the left limb omitted ; underside view of penis placed in juxtaposition with the preceding 

 figure (dried). 



Figs. 39. At. tarsaUs: — wings; legs (1-3) of ^ ; underside view of forceps aud penis (dried). 



Figs. 40. Th. determinatus : — wings, slightly defective ; intermediate leg aud hind leg of ^ ; underside 

 view of genitalia, showing the forceps -basis, the left forceps-limb, and the penis (dried). 



Plate XXIII. 



Neuration of the Ecdyurus type, exhibiting differences, for the most part fortuitous, in the connections 

 established between the adventitious uervures aud the main nervures of wings, which are of no 

 generic significance. The fore wings were selected chieflj' for the purpose of demonstrating 

 diverse common combinations of the adventitious or intercalar nervures of the aual-axillar 

 interspace (defined at page 81) ; but fig. 43 has reference to those of the sectorial group, 

 and (like fig. 42) shows how a spurious " apical fork " may be originated. The figures are 

 all enlarged. 



Figs. 41. Pcegniodes cupulatus: — hind wing and part of a fore wiug. 



Fig. 42. Compsoneuria spectabilis : — wings. It may be doubted whether the remarkable paucity of 

 cross-veinlets in the fore wing is a constant generic characteristic. 



Fig. 43. Rhithrogena semicolorata : — part of a fore wing, showing an occasional combination of sectorial 

 intercalary nervures. 



Figs. 44. " Epeorus " [—Iron] longimanus : — wings and parts of fore wings of three different specimens. 



Fig. 45. Heptagenia gaUica : — -fore wing. 



Fig. 46. Ecdyurus i'eno.?u.i : — hind wiug, showing a denser condition of tlie adventitious neuration of the 

 terminal border than obtains in the other wings figured. This is not of generic import. 



Plate XXIV. 



Limbs and genitalia of 41. Ptegniodes, 42. Compsoneuria, 43. Rhithrogena, 44. Iron, 44 a. Epeorus, 

 45. Heptagenia, and 46. Ecdyurus : — all enlarged. — -N.B. Pages 234-236 of the letterpress 

 should be consulted on account of the possibility of some of the legs and tarsi represented iu 

 this Plate being deformed. 



Figs. 41. P. cupulntus: — legs (1-3) of V [the intermediate is defective] ; underside view of penis aud 

 the left forceps-limb (dried). 



Figs. 42. C. spectabilis: — fore and hind leg of ? ; underside partial view of genitalia (dried). 



Figs. 43. Rli. semicolorata : — legs (1-3) of ^ and fore leg of § , with more enlarged views of the 

 corresponding tarsi ; underside views of penis (43^ and 43°) freshly killed and (43') dried. 



Fig. 43 «. Rh. " seniiti?i,cta"[ = alpestris'] : — underside view of peuis (freshly killed). 



Fig. 43 b. Rh. germanica : — underside view of penis (dried). 



Fig. 43 c. Rh. Hageni : — underside view of penis (dried). 



Fig. 43 d. Rh. aiirantiaca : — fore tarsus of $ (alcoholic) . 



Pigs. 44. I. longimanus : — legs (1-3) of r? aud fore leg of ? , with more enlarged views of the corre- 

 sponding tarsi (dried). 



