268 BULLETIN : MUSEUM OF COMPAEAT1VE ZOOLOGY. 



Less exact references have been made to Tenthredo by Schoberlin ('88), two 

 species from Oeuingen; Serres ('29) and Heer ('61), species from Aix; and 

 Schlotheim ('29), one from Baltic amber. These last cannot be regarded as 

 generic determinations, and have no especial significance in the present state 

 of our knowledge. 



Florissant species of Tenthredo. 



1. Anal cell of hind wings sessile with or touching the first apical cell ; dis- 



coidal cell of front wings very long, its diagonal length much more than 



twice the length of the basal nervure T. avia, sp. nov. 



Anal cell of hind wings shorter, not touching the first apical cell, but sepa- 

 rated from it by a distinct vein or petiole 2 



2. Petiole of anal cell in hind wing over one-half the length of the basal 



nervure of the front wing, equalling the vein closing the second dis- 



coidal cell of hind wing T. infossa, sp. nov 



Petiole of anal cell very short, less than one-third the length of the basal 

 nervure 3 



3. Length 13 mm. First discoidal cell over four times as long as the basal 



nervure in the front wing T. submersa Ckll. 



Length 17 mm. First discoidal cell less than three times as long as the 

 basal nervure T. misera, sp. nov. 



Tenthredo avia, sp. nov. 



Female. Length about 13 mm. Body probably variegated with yellow and 

 black. The head is black and the antennae dark. Dorsum of thorax brownish 

 black at the bases of the wings and paler along the parapsidal furrows. Scutellum 

 yellowish; metanotum yellowish, with black reticulations. Median groove of 

 mesonotum very distinct. Abdomen apparently very pale, with a dorsal line of 

 spots, one to each segment; these are small, rounded-quadrate, and diminish 

 in size apically. Wings hyaline, the veins unusually pale in color. Median cell 

 shorter than the submedian by only one-half the length of the transverse median 

 nervure. Third submarginal cell more than twice as high at the apex as at the 

 base. Anal cell not contracted at the insertion of the cross-vein ; its sides sub- 

 parallel, but the posterior side suddenly widens out basally, making the cell more 

 than twice as wide as at the cross-vein. Posterior wing with the anal cell not 

 separated from the first apical cell by a vein. 



Type. No. 2046, Mus. Comp. Zool., Florissant, Col. (No. 3763, S. H. Scudder 

 Coll.). 



Of the four species from the Florissant shales, this most closely approaches 

 recent representatives of the genus. The preservation of the type is very good, 

 except the sides of the abdomen, which are not distinguishable at first glance. 

 This causes the abdomen to take on a singular subulate appearance quite foreign 

 to its actual form. 



