450 SAMUEL II. SCUDDER ON 



The wing is exceedingly slender and subcuneifonn, being nearly four times longer than 

 broad, it- greatesl breadth jusl before the middle, both costal and inner margins gently 

 arcuate, and the tip somewhat produced. The outer half of the inner margin appears to 

 be slightly broken, bul is apparently narrowed to the very slightest degree. The hu- 

 meral field is large, flat, rather regularly cuneiform, reaching about two-fifths way down 

 the costal margin, separated by a ridge (furrow, if it were- viewed from above) from the 

 adjacent pails. The mediastino-scapular vein is strongly sinuous and terminates far 

 below the tip of the wing, so that the costal area, which in the entire apical half of the 

 wing occupies more and generally much more than half the breadth, embraces the entire 

 tip and is filled with regular, straight or gently arcuate, simple or forked, parallel, not 

 crowded branches. The externomedian and internoinedian areas divide equally between 

 them what little space is left between this broad costal ana and the anal furrow. The 

 anal area is large, the furrow, which is no more prominent than the other veins, being bent 

 roundly and sharply in the middle, and yet reaching- almost as far as the humeral field, 

 and as far as the basal fork of the externomedian vein. No anal veins are preserved. 

 The externomedian branches are only three or lour in number, sinuous and longitudinal; 

 those of the internomedian quite as lew, nearly straight and oblique. 



The length of the wing is 10 mm.; its breadth, 2.6 mm. It comes from the English 

 Purbecks, and according to Westwood, from the lower members at Durdlestone Bay. 



It is possible that the obscure specimen figured in PI. 46, fig. 6, also belongs to this 

 species. It is too imperfect to determine. The slenderness of the wing and the resem- 

 blance of the humeral field and anal furrow are very similar, but the form is less tapering, 

 and the nervules, especially toward the tip, are much more crowded and more directly 

 longitudinal. It is possible, however, that it should be represented as broader, as the 

 inner edge comes against a slight elevation in the dirty chalky-white stone. Perhaps a 

 closely allied species is indicated. It comes from the English Purbecks and was sub- 

 mitted to me with the other by Mr. Brodie. 



Another species, apparently belonging to this genus, is indicated by the obscure speci- 

 men figured in PI. -16, fig. 8. It differs from any in the decided tapering of the apical 

 half to an almost pointed tip, but the neuration is too imperfect to indicate any further 

 characters. Probably the right hand margin is the costal. The wing is flecked with 

 reddish-brown, contrasting with the light brown color of the stone, the veins dusky. Its 

 length is 1:27) mm., and its breadth. 2.6 mm.; and like the last it comes from the English 

 Purbecks and was communicated by Rev. Mr. Brodie. 



Rithma? minima sp. now 

 PI. 48, Bgs. -.',8a, 8gr, 11. 



[Without name | figured with others by Westwood, Quart. Journ. Geol. Soc. Lond., x, 

 383-384, PI. 15, fig. 11, the uppermost and the left hand of the two lowest objects. 

 Two objects which probahfj belong together, as their relative sizes agree perfectly, 



are found on the same light brown stone, and are referred here from slight indications 



