Scolytidic.] RHYXCHOPHOUA. 403 



reception of the legs ; eyes round, subcouvex ; bead broa.lcr 



than thorax PLATTPODIN.E. 



SCOLYTINJE. 



This sub-family contains the whole of the genera of the Scolytidae with 

 the exception of Platypus, from Avhich it differs as above stated; the 

 shape of the various genera is somewhat variable but is almost always 

 cylindrical; in the subdivision into tribes and species good characters 

 are afforded by the sculpture of the thorax, which is in many cases 

 furnished with strong warty asperities in front, and by the formation of 

 the apex of the elytra which is often more or less excavate and, in one 

 sex at least, dentate ; the shape of the club of the antennae and the 

 number of joints of the funiculus of the antennae are also of great im- 

 portance. 



The sexual differences are in many cases very marked, the males in 

 some instances differing entirely from the females and being extremely 

 rare. Our species may be divided into the three following tribes : 



I. Thorax not prolonged over the head which is always in part 



rile from above and is terminated by a short snout ; thorax 



without any marked asperities on its anterior portion ; third 



tarsal joint nearly always bilobed.* 

 i. Abdomen strongly raised obliquely from near apex; thorax 



bordered at sides SCOLYTIXA. 



ii. Abdomen not, or only slightly, raised, as a rule regularly 



cylindrical ; thorax not bordered at sides HTLESIXIXA. 



II. Thorax prolonged over the head, which is sunk in the thorax 



when the insect is at rest, and is more or less globose ; thorax 

 almost always furnished with more or less distinct warty 

 asperities in front ; third tarsal joint simple DRYOC-BTIJ.A. 



SCOLYTINA. 



This tribe comprises the single genus Scolytus, which may easily be 

 known by the shape of the abdomen and by its short broad form, pro- 

 jecting head, and the absence of asperities in front of the thorax, which 

 is usually finely punctured, and very shining ; the thorax is margined 

 at sides and base ; the scutelluin is distinct and sunk in a deep impres- 

 sion, and the elytia are not excavate and only slightly sloped at apex ; 

 the antennse are inserted near the eyes and are 11-jointed, with a large 

 club which is longer than the funiculus ; the latter is composed of seven 

 joints ; the tibia? are armed externally with a strong hook and the third 

 joint of the tarsi is broad and strongly bilobed ; the posterior coxie are 

 rather widely distant ; the species are very destructive to trees, and 

 appear to attack especially the elm, oak, hornbeam and birch, besides 

 various fruit trees ; none of them appear to attack Coniferce. 



* This character is indistinct in the smaller species of Hylesinus, and is absent only 

 in one genus, Polygraplws ; in the Dryocsetina there may occasionally be a vestige of 

 a siiout, but it is not iouud iu auv indigenous genus. 



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