THE MELANDRYID BARK BEETLES. 



1287 



Horn, in his latest paper above cited, divides the family into ten 

 tribes. Of these representatives of seven have been taken in In- 

 diana, while those of two other-; probably occur. 



KEY TO INDIANA TRIBES OF MELANDRYIMS. 



a. Next to last joint of all the tarsi simple; front tarsi of males not di- 

 lated; thorax as wide at base as elytra, 

 ft. Antennse with last three or four joints suddenly larger, forming a 

 loose, strongly developed club; length less than G.5 mm. 



Tribe I. Tetratomini, p. 1287. 



bl). Antennae gradually thicker or filiform. 



c Front coxal cavities with an outer fissure or cleft. 



d Third joint of antenna as long as fourth and fifth together ; form 

 broadly oval. Tribe II. Penthini, p. 1280. 



dd . Third joint of antennae not much longer than fourth; form elon- 

 gate. 



e. Front coxa not prominent, rather widely separated; species 

 stronglv resembling Melanotus; length 10-11 mm. 



Tribe III. Synchroini. p. 1200. 

 ee. Front cox* moderately prominent and nearly contiguous; color 

 piceous; length 6-8.5 mm. Tribe IV. Mai.t odryini. p. 1291. 

 cc Front coxal cavities without fissure; form oval or oblong, convex. 



Tribe V. Orchesiini, p. 1201. 

 aa Next to last joint of front and middle tarsi excavate and emarginate. 

 more or less lobed beneath; front tarsi of males delated. 

 f. Tarsal claws simple or very slightly broader at base; thorax as wide 

 at base as elytra. 



g Head not constricted behind. Tribe VI. Melandryini, p. 1295. 

 eg. Head suddenly constricted behind the eyes; small species, not over 

 5 mm. in length. Tribe VII. Scraptiini, p. 1200. 



ft Tarsal claws with a broad tooth or lobe at base. 



Ji Middle coxal cavities open on the outer side; head not prolonged; 

 thorax as wide at base as elytra, its side margins entire, acuta 



Tribe VIII. Xothint, p. 1301. 

 hh Middle coxal cavities enclosed by the sterna; head more or less 

 prolonged in a beak; thorax not as wide at base as elytra its 

 margin evident at base only. Tribe IX. Mycterini. p. 1302. 



Tribe I. TETRATOMINI. 

 This tribe comprises small, oval convex forms living in fungi 

 and havin- the last three or four joints of antenme much enlarged, 

 nearly equal in size and forming a loose club; tibial spurs small; 

 next to last tarsal joint not lobed, claws simple, cox* all separated 

 by their respective sterna. Casey, locality cited, has divided the 

 tribe into five genera, three of which are represented m the State, 

 while a single species of another may occur. 



