KEV. A. E. EATOIS ON KECENT EPHEMEEID.E OK MAYFLIES. 77 



sector are pitch-black; but the costa, subcosta, and radius, tog'ether with the cross 

 veiulets of the marginal and submarginal areas, are in opaque view bistre-grey, and 

 in transmitted light pale golden brown, or brownish amber-colour. Set* dull light 

 yellowish white. 



? (dried) very similar. The wings towards the base, especially in the marginal area 

 of the fore wing, tinted with lurid. 



Length of body, d 17-19, 2 17-20; wing 18-19; sette, d 40-50 & 5, subim. 18 & 

 4-5, ? 13 & 10-5-20 & 15 mm. 



Sab. Near Hock Island, Illinois, and in Texas (Walsh & M'Lach. Mus.). The part of 

 the dorsal stripe in each segment of the abdomen is quadrangular, nearly straight at the 

 sides, and only a little broader in front than behind. 



Pentagenia quadri-punctata, Walsh. 



Pentagenia quadripunctata, Walsh, Proc. Ent. Soc. Philad. ii. 198 (1863); Etn., Traus. Ent. Soc. 

 Loudou (1871), 64. 



This species is diagnosed by Walsh as differing from F. mttigera in the following 

 details. The part of the dorsal stripe in each segment of the abdomen is angulated at 

 the sides and hexagonal in form. In the fore wing a series of four distinct fuscous dots, 

 surrounded each by a slight cloud, is extended transversely in a slight curve from the 

 middle of the costa to the midst of the wing (the dots presumably corresponding with 

 buUte), marking the subcosta and the 4th, 6th, and 9tli longitudinal nervures from the 

 costa. Wings of subimago opaque whitish. Length of body, j 19, $ 19-5-22; wing, 

 cf 15 ; $ 18-19-5 ; seta?, 2 im. 22-5 & 19*5, subim. 17 & 14, 6 subim. 15 & 3 mm. 



Rab. Hock Island, Illinois. 



Part II. Read February 7th, 1884. 



Group II. of tue Genera. 



Adult. — At the fore-wing roots the anal nervurc (8) communicates with the pobrachial 

 (7) only by means of an obsolete channel of circulation permeating the membrane in 

 proximity to the prominent curved or angulated fold that meets the basis of the radius 

 (3) [excepting perhaps in Tricorythus and Cceiiis (PL XV. 25 and 26). N.B. In PL IX. 

 the figure of part of the wing of RhoenantJms, 15, is defective thereabouts]. Legs all 

 functional ; hinder tarsi with 4 distinct joints, and sometimes with colour-indications of 

 a fifth joint intimately concrete with the tibia {i.e. not definitely limited by suture) ; 

 ungues rather small. Contour of 6 oculi various in different sections. Nijmjoh. — Palpi 

 of both pairs of maxillte 3-jointed. [Exceptions : palpus of maxilla I. 4-jointed in Fros- 

 opistoma, 2-jointedin Callibaiis ; palpus of maxUla II. with joint 3 ill defined in Baeiis.'] 



First Series of Group II. 

 Adult. — The anal (8) and bifid 2nd axillary nervures, together with the inner margin 

 of the fore wing, enclose a semisagittate space ; the 1st axillary nervure (9') conniveut 



second series. — ZOOLOGY, VOL. III. 11 



