32 



arcuate sutures on each side, Pityopthorus (PL 10, fig. 22), or the inner margins 

 of the segments may be thrust towards or to the apex of the club so that the 

 segments lie obliquely and the sutures show only at the apex or not at all upon 

 the inner face, Ips', when in addition to this condition the club is thickened 

 towards the base with the apical segments more or less completely telescoped, 

 an obliquely truncate club is produced, as in Xyleborus, Anisandrus, Dryocoetes, 

 Pityokteines, and Orthotomicus (PL 10, fig. 32), where almost the entire club is 

 formed by the first segment. The distal segments are distinctly evident in 

 Orthotomicus. In widely separated genera, Pityophthorus and Eccoptog aster, the 

 sutures of the club are very strongly chitinized, resulting in a partial or complete, 

 distinctly visible septum. In a few genera the club is unsegmented, Chramesus 

 (PL 10, fig. 36), Polygraphus (PL 21, fig. 1). 



The funicle comprises that part of the antenna between the 1st segment, 

 called the scape, and the club. The 1st segment of the funicle, known as the 

 pedicel, is always enlarged; the remaining segments, comprising the outer part 

 of the funicle (or the funicle of European writers) vary in number from one to 

 six, usually widening towards the club. The number of segments in the funicle 

 is usually a valuable character, but must be employed with caution since in some 

 genera, Polygraphus, the number may vary in the same species. The scape is 

 usually elongate, frequently strongly arcuate at the proximal end and clavate 

 distally; sometimes short, Eccoptogaster (PL 10, fig. 8); rarely much widened 

 and flattened, Micracis (PL 10, fig. 19). 



The antennae bear many important characters, used repeatedly in the tables. 

 They may often be examined satisfactorily with a good lens without removing 

 them from the head, but very frequently it is necessary to remove and mount 

 them in balsam. 1 



The epistoma presents valuable characters in the median lobe, variably 

 developed, as in Phleeosinus; the dorsal process, Dendroctonus (PL 9, fig. 37, 38); 

 the median carina, and the punctuation and pubescence. The margin bears 

 a fringe of stiff, light-coloured hairs. 



The front bears important characters frequently used in the keys. Most 

 important are the impressions, punctuation, granulation, median carina, and 

 pubescence. Very often the sexes show marked difference in frontal characters. 



THE THORAX. 



The pronotum is somewhat depressed in the Hylesinince and Eccoptogas- 

 terince', usually strongly arcuate or gibbose in the Ipince and Micracince, although 

 in a few genera, Dryocoetes and Xylocleptes, the convexity is less pronounced. 

 The characters present in our genera concern the shape, punctuation, asperities 

 of the frontal portion, granulation, pubescence, sub-basal line or margination, 

 and the condition of the lateral margin. 



On the ventral surface of the prothorax the length and concavity of the 

 prosternum with the prosternal ridges are important, and also sometimes the 

 punctuation of the lateral areas. 



/Pin the mounted beetle securely to a cork angle. With a needle, kept moist with clearing mixture 

 until the antenna is secured, work the antenna loose under a dissecting microscope, or a strong lens held 

 in the left hand. Transfer the free antenna on the moist needle point to a drop of 98 per cent alcohol on 

 a clean slide. When the alcohol is nearly evaporated add a drop of carbol-xylene, (xylol, one-half, 

 melted carbolic acid crystals, one-half). When this is nearly evaporated add xylol-balsam and cover. 



^ The angle used by the writer for this purpose is made of sheet cork; it has a base 4 inches long by 

 3 inches wide, covered above with soft white paper, with a vertical back 1J inches high, and a rim of 

 Bristol board one-quarter of an inch high pinned securely about the sides and front. 



Exceedingly fine needles are necessary for removing very small antennae, and for all fine dissection 

 under high power. The best needles known to us are those used by dentists for extracting nerves. These 

 may be obtained either plain or with serrated edges, together with suitable handles from any dentist, 

 or dealer in dentist supplies. The plain needles may be bent into any desired curve by drawing the point 

 between the thumb and fore finger. They are exceedingly durable. 



