8 LAEV^ OF THE PEIONIN.^. 



ampulla of Perris). Spiracles oval annuliform, two-lipped, respira- 

 tory opening narrow; lips membranous, clothed with setigerous 

 tubercles. Anal lobes three (rarely two), exserted. 



Key to the Subfamilies of Cerambycid^. (Plate I.) 



Head transverse, broader than long. 



Epistoma projecting over clypeus; front projecting over epistoma, dentate 

 or carinate (except Pamnc?m); clypeus as wide at base as epistoma; man- 

 dibles acute. Legs present Prionin^. 



Epistoma not projecting; front smooth and rounded. 



Mandibles acute; clypeus occupying space between condyles. 



Sides of epicranium meeting behind front, fused for some distance, 

 then separating. Dense brush of hairs on gena behind pleiu-o- 

 stoma. Ninth abdominal segment bearing a pair of chitinous 



spines. Form cylindric Asemin^. 



Sides of epicranium meeting behind front, then separating (not 

 fused), angulate. Caudal spines usually absent. Lateral zone 

 usually distinct on all abdominal segments. Form depressed. 



Lepturin^. 

 Mandibles with cutting edge rounded (gouge shaped). 



Clypeus not as wide at base as epistoma Cerambycin^e. 



Head oblong, sides parallel or narrowing behind. 



Clypeus as wide at base as epistoma; mandibles obliquely acute. Sides 

 of epicranium behind front fused for entire distance. Legs absent 

 (rarely present) Lamun^ . 



GENERAL ANATOMICAL CHARACTERISTICS OF THE PRIONIN^.^ 



The larvae of the Prioninae form a very natural, distinct, and easily 

 recognized group. In form they are of large size, robust and re- 

 markably glabrous, cylindric or tapering posteriorly. 



The head is large, robust, strongly chitinized in front and widening 

 posteriorly; it is deeply embedded in the pro thorax. The dorsal margins 

 of the epicranium are partly fused behind the triangular front, then 

 separated, giving a deep emargination behind. The epistoma (PI. I) 

 is characteristic in North American forms (except Parandra) of this 

 group in that it projects over the posterior angles of the clypeus in 

 two triangular lobes, more or less distinct or connected; it bears 

 three distinct setae on each side (epistomal setae, PI. III). The 

 anterior margin of the front (PL I) is produced over the epistoma 

 into a dull or dentate carina {Prionus, Mallodon, and Orthosoma) or is 

 variously modified into teeth or tubercles (Ergates, Tragosoma), af- 

 fording characters of good specific value (PI. III). Anterior to the 

 epistoma is the trapezoidal membranous clypeus, to which is attached 

 the more coriaceous semicircular or cordate labrum. 



1 The terminology used here follows in part that of Dr. A. D. Hopkins, "Contributions Toward a Mono- 

 graph of the Scolytid Beetles. I. The Genus Dendroctonuo." U. S. Dept. Agr., Bur. Ent., Tech. Ser. 17, 

 pt. 1, 164 p., 95 figs., 6 pi., June 30, 1909; also Dr. A. Boving, "On the Abdominal Structures of Certain 

 Beetle Larvae of the Campodeiform Type." Proc. Ent. Soc. Wash., v. 16, no. 2, p. 55-61, pi. 3-6, June, 1914; 

 Snodgrass, R. E., "The Thorax of Insects and tlje Articulation of the Wings." Proc. U. S. Nat. Mus., 

 V. 36, p. 511-595, pi. 40-69, June 18, 1909, separate No. 1687; Crampton, G. C, "A Contribution to the Compar- 

 ative Morphology of the Thoracic Sclerites of Insects." Proc. Acad. Nat. Sc. Phila., v. 61, p. 3-54, 21 figs. 

 4pl., Jan. ,1909. 



