NATURAL SCIENCES OF PHILADELPHIA. 237 



lis; the lustre is somewhat leaden, owing to the very fine and dense sericeous 

 pubescence with which it is clothed. The 9th joint of the antennae is flat, 

 nearly oblong, and more than twice as long as its width ; the 10th is trian- 

 gular, and narrowed at the base ; closely joined to the 11th, which is not 

 longer than its width, shorter than the 10th, and rounded at tip; the 10th 

 and 11th together are shorter than the 9th. 



The antennae are described by Boheman as having but two elongated ter- 

 minal joints ; unless the student would consider such a form impossible in 

 this type, the union between the 10th and 11th joints might be readily over- 

 looked, and the antennas thus erroneously described. 



Subgboup III. XYLETINI. 



The species of this subgroup are generally oval in form, rarely subelongate, 

 and, except in some species of Xyletinus, have the contractile power consid- 

 erably developed. The head, when inflexed, extends beyond the excavated 

 under surface of the prothorax, over the mesosternum, so that the man- 

 dibles attain the metasternum, and in most the genera lie in close apposition 

 with its anterior margin. The head is deeply excavated each side in the gu- 

 lar region for the reception of the antennae, which in repose are curved into 

 these cavities, and do not lie between the coxae. The front coxae are contig- 

 uous and depressed ; the middle feet are frequently received in excavations 

 of the meso- and metasternum, and the knees rest in a subhumeral cavity of 

 the epipleurae. The first ventral segment is sometimes excavated for the re- 

 ception of the hind legs, sometimes not ; the epipleurae are foveate for the 

 hind knees in Protheca. The metasternum is never prolonged and lobed 

 in front of the middle coxae, as in the next subgroup, but is broadly truncate, 

 on a line with the coxae, when the latter are widely separated. The mandi- 

 bles are always broadly dilated at the base. The antennae are variable in 

 shape, being sometimes serrate or subpectinate, and sometimes having the 

 last three joints dilated, forming a long, loose club. 



The European genera Mesothes and Mesoccelopus, with the first ventral seg- 

 ment excavated for reception of the hind feet, the antennae serrate, and the 

 front coxa? contiguous, probably belong to this subgroup. 



Elytra striate, antennas serrate Xyletinus. 



Elytra not striate ; first ventral segment not 

 excavated : 



Antenna; serrate Lasioderma. 



Antennas with the last three joints large ?Catorama. 



First ventral segment excavated : 



Epipleurae not foveate at the middle Hem iptychus. 



Epipleurae foveate at the middle P r o th e'ca. 



XYLETINUS Latr. 



Our species differ notably in form; in the first the body is cylindrical, 

 and the head but feebly excavated beneath for the reception of the antennae ; 

 in the others (typical Xyletinus) the head deeply excavated each side beneath. 

 The metasternum is declivous in front, but the declivous portion is not sharply 

 defined by a transverse line, as in the two following genera. 



1. X. peltatus. Anobium pdtatum Harris, Trans. Hartf. Nat. Hist. Soc, 

 75. Throughout the Atlantic States, not common. 



'i 



2. X. mucoreus, cylindricus, piceus opacus, alutaceus, dense sericeo- 

 pubescens, thorace punctulato convexo, latitudine duplo breviore, lateribu3 

 obliquis paulo rotundatis, angulis posticis valde obtusis rotundatis, elytria 

 striis subtilius punctatis, interstitiis planis parce subtiliter punctulatis ; palpis 

 antennisque ferrugineis, his articulo primo piceo. Long. -26. 



One specimen from Louisiana in the collection of Mr. Ulke. Resembles 



1865.] 16 



