650 FAMILY IV. SCOLYTIDJE. 



1050 (9097). THYSANOES RIGIDUS Lee., 1876, 362. 



Dark brown, somewhat shining. Form stout, cylindrical, somewhat 

 oval, clothed with rather long, erect, pale bristles. Prothorax a little 

 wider than long, convex, anterior edge not toothed, disc with a few dis- 

 tant. acute tubercles in front of middle, sparsely punctured behind. Ely- 

 tra punctured in rows, setigerous punctures of interspaces very small. 

 Legs and antennae yellow-brown; club oval, hairy, sutures curved, surface 

 rather shining. Male,* front with a small rounded, polished excavation. 

 Length 1 mm. 



Known from Canada and Michigan. Dr. Hopkins states in a 

 letter that this species belongs to the Micracini. 



Thysanoes quercus Hopk., Mss., is an undescribed species, cited in 

 Smith's List of New Jersey Insects, infesting the bark of dead oak and 

 chestnut twigs. Eagle Rock, near Newark, New Jersey. (Bischoff.) 



Tribe V. CRYPTURGINI. 



Body slender to moderately stont ; pronotum longer than 

 broad, (or at least not broader than long), commonly smooth in 

 front; antennal club subglobose, compressed, never conical (Fig. 

 137, H) ; head exposed or rarely concealed from above; eyes sim- 

 ple ; base of elytra simple. 



KEY TO GENERA OF CRYPTURGINI. 



a. Third joint of tarsi simple, fourth joint distinct. I. CRYPTURGUS. 

 aa. Third joint of tarsi expanded, usually heart-shaped or bilobed. 



II. DEXDROCTONUS. 



I. CRYPTURGUS Erichs., 1836. (Gr.. "hidden" + "laborer.") 



Very small, cylindrical, elongate species (1 1.5 mm.) in 

 which the thorax is simply punctate and elytra unarmed on de- 

 clivity; set aside by all authors on account of the 2-jointed 

 funicle. One species atonms LeConte (1868) is generally re- 

 garded as identical with Gyllenhal's puslUns (though retained 

 as distinct by Swaine), found in Europe and Japan. Another has 

 been made known by Schwarz, under the name alutaceus. Both 

 differ in habitually making use of the galleries of other bark 

 beetles in entering the trees. (Fig. 139, E.) 



*Schwarz (Ent. Amer., II, 42) says he believes this description applies to the female; 

 what he takes for male has the head deeply retracted in thorax, so the sculpture cannot 

 be seen; but the first antennal joint is fringed with a double row of long pale hair, as 

 in certain species of Micracis. 



