18 D. S. FLETCHER 



inclined towards uncus, apical area and margin scobinate; setose projection 

 from basal fourth of dorsal process of valve long and slender (Text-fig. 351) 



principis-group (part, tricuspida) (p. 209) 



- Lateral processes of uncus rounded, or slight and inclined laterally. Valve 



differently formed . . . . . . . . . .32 



32 (31) Lateral processes of uncus rounded. Valve with a coarsely spined ridge 



along apical half of ventral margin; a second, shorter ridge nearer apex, 

 sometimes symmetrical; setose projection from basal fourth of dorsal pro- 

 cess of valve long and slender (Text-fig. 416) . crystallophana-group (p. 245) 



- Valve not so formed .......... 33 



33 (32) Apical half of uncus slender, basal half dilate laterally and setose. Fulcrum 



extending to tip of aedeagus, scobinate at apex ..... 34 



- Uncus triangular, with short, setose, shoulder-like projections. Apical area 



of valve tapered and scobinate on inner surface, ventral margin slightly 

 produced. Fulcrum atrophied, little longer than width of aedeagus 

 (Text-fig. 425) ..... tullia-group (part, tullia) (p. 251) 



34 (33) Valve tapered, narrowed by one-half from base to rounded apex (Text-fig. 



435). Vesica without cornuti ..... cafon-group (p. 257) 



- Valves with apical processes. Vesica with a cluster of short cornuti . . 35 



35 (34) Dorsal and ventral apices of each valve each with a smooth, digitate, sclerotized 



process (Text-fig. 403) .... reflexaria-group (part, ixiaria) (p. 233) 



- Dorsal apex of each valve with two tapered, sclerotized processes, smooth or 



scobinate; ventral apex with one sclerotized and one short, membranous 

 process (Text-figs 413, 415) ...... pristis-group (p. 243) 



36 (27) Uncus spatulate and rectangular; or little tapered apicad, the apical margin 



being truncate and straight-edged. Apical margin of ventral plate of 

 gnathus arcuate or bilobate (Text-figs 347, 349) 



principis-group (part, pvincipis, platycephala, xyele) (p. 209) 



- Uncus not so formed .......... 37 



37 (36) Uncus tapered to truncate apex, apical margin not less than one-half width 



of base; a short, peg-like projection extends from ventral surface of apical 

 margin. Ventral plate of gnathus well developed and strongly sclerotized, 

 apex rounded 



principis-group (part, onycha, bicuspida, gamma, consummata) (p. 209) 



- Uncus not so formed .......... 38 



38 (37) Uncus almost circular with knobbed, ventral projection (Text-fig. 353). 



Ventral plate of gnathus with a pair of strongly sclerotized, drumstick-like 

 projections extending caudad. . principis-group (part, clavigera) (p. 209) 



- Uncus simple, tapered to a point or to a blunt or a rounded apex; dorsal 



surface sometimes with a keel-like ridge, often densely setose 39 



39 (38) Fultura superior sclerotized medially. Ventral plate of gnathus not developed . 40 



- Fultura superior wholly membranous ....... 41 



40 (39) Fultura superior coarsely scobinate. Valve tapered to sharply pointed apex; 



a short, spine-like projection from mid-dorsal margin; inner surface smooth. 

 Vesica with one or more cornuti ..... xystra-group (p. 126) 



- Fultura superior minutely and densely scobinate. Valve tapered to sharply 



pointed apex, or apices of both dorsal and ventral margins bearing each a 

 short spine at tip (Text-figs 286, 290) ; inner surface of valve with numerous 

 parallel, sclerotized ridges in apical half. Vesica without cornuti 



/essa-group (p. 170) 



41 (39) Heavily sclerotized medial core of fulcrum acicular or tipped with two or 



three spines; apical third or fourth curved through 90 degrees to point at 

 five-sixths aedeagus, the membranous or weakly sclerotized sheath of 



