66 bulletin: museum of comparative zoology. 



two veiy pronounced longitudinal carinae that originate near the basal angles, 

 curve centrally and divide the segment into three nearly equal parts; they 

 continue in a slightly divergent direction on the basal half of the second seg- 

 ment. Second segment at apex one-half wider than long; third, fourth, and 

 fifth of about equal length. Wings hyaline, veins fuscous. Stigma and 

 marginal cell long and narrow. Areolet subtriangular, with a long petiole 

 above. Discocubital vein rather sharply curved at its middle. Submedian 

 cell much longer than the median. 



Three specimens. 



Type — No. 2241, M. C. Z., Florissant, Col. (No. 5447, S. H. 

 Scudder Coll.). Also two specimens later sent by Professor Cockerell, 

 Nos. B3 and B5. 



This is a peculiar species and seems to be best regarded as Tyle- 

 comnus as I cannot find any other genus to which it may be cer- 

 tainly referred. The areolet will distinguish it from the other fossil 

 species just as this character forms two groups among living species. 



Ophioninae. 



This group is well represented at Florissant by 23 species belonging 

 to eleven genera, all but two of which are known by living species. Of 

 these, three (Anomalon, Limnerium, Mesochorus) are especially 

 prominent and are each represented by several species and numerous 

 specimens. There have previously been recognized from the Tertiary 

 in other parts of the World four genera, three of which, Mesochorus, 

 Anomalon, and Porizon occur at Florissant, but only two species have 

 been described, one Anomalon by Heer from Oeningen and one 

 Mesochorus from Green River, Wyoming by Scudder. The latter was 

 made the type of a new genus Lithotorus by Scudder, but it is evidently 

 a true Mesochorus being much more typical than any of the several 

 species here described from Florissant. 



The small group Hellwigiini is represented by two living genera, 

 both of which occur in the Old World. From Florissant, I have 

 recognized a third which shows undoubted affinities with Hellwigia, 

 although it is more generalized in several respects as can be seen 

 from the following diagnosis. 



Protohellwigia, gen. now 



Slender species of rather large size. Abdomen with a long slender petiole. 

 Antennae about two-thirds the length of the body, rather distinctly thickened 



