NO. 1930. DESCRIPTIO?,\'i OF NEW SAWFLIES—ROHWER. 245 



ments in the middle and margin of sheath black; head below antennae, 

 angles of pronotum, tegulse and legs luteous. Wings hyaline, iri- 

 descent; venation pale brown, costa and stigma pallid. 



Oxbow, Saskatchewan, Canada. Two females, one June 19, 1907 

 (type), the other June 15, 1907, collected by Frederick Knab, for 

 whom the species is named. 



Type.—Csit. No. 14559, U.S.N.M. 



In the paratype the intraocellar area and fifth tergal segment are 



pale. 



Genus NEMATUS Panzer. 



NEMATUS PROCIDENTIUS, new species. 



Related to the European Nematus crassus Fallen, but may be 

 separated by the rufous coxae, white tarsi and dilTeent conformation 

 of the procidentia. 



Male. — Length 9 mm., slender; antennae 8 mm. Ijabrum broadly 

 rounded apically; ch^peus deeply, arcuately amarginate, lobes 

 broadly triangular; supraclypeal area gently convex; supracl}q)eal 

 foveae deep, oval in outline; middle fovea with sloping sides, rather 

 deep and m middle circular in outline; ocellar basin pentagonal, 

 lateral walls well defined, lower walls rounded; frontal crest produced, 

 unbroken ; postocellar line distinctly longer than the ocellocular line ; 

 postocellar area more than three times as wide as the cephal-caudad 

 length; head with fine, irregular punctures; antennae long, tapering, 

 the third joint shorter than the fourth; prescutum with rather close, 

 fine punctures, which become sparser on the scutum and practically 

 wanting on the scutellum; stigma rounded below, apex tapering; 

 first transverse cubitus wanting; legs normal; hypopygidium very 

 long, obtusely triangular; last dorsal segment depressed on each 

 side of the middle so the elevated portioh is /n"~X shaped; proci- 

 dentia scarcely produced, flattened apically; in the type the tenth 

 dorsal segment is much produced. Black; legs except apical half of 

 the posterior tibiae (which are black) and the tarsi (which are whitish) 

 red; tegulae white. Wings clear hyaline, iridescent; venation dark 

 brown. 



Conewago, Pennsylvania. ©One male collected June 23, 1911. 

 Keceived from Mr. V. A. E. Daecke. 



Type.— C&t. No. 14412, U.S.N.M. 



Family PTERYGOPHORID.E. 



Genus ACORDULECERA Say. 



In describing the antennae of this genus it has been stated that 

 they are six jointed. This is an error, as they are really seven jointed, 

 \ there being a small joint between the pedicellum and flagellum (see 

 ! figure 6a and 6&). In one of the species described below the two 



