214 
MR WALTER RITCHIE ON THE STRUCTURE, BIONOMICS, AND 
pilose pubescence ; head somewhat ^strongly produced, distinctly punctured ; 
antennse ferruginous ; thorax near base about as broad as or a little broader than 
long, much narrowed and somewhat compressed in front, rather finely punctured, 
the punctuation, however, being variable in different specimens and being closer 
and stronger at sides than on disc ; scutellum rather large, punctured ; elytra 
separately and broadly rounded at base, with comparatively fine punctured strise ; 
interstices punctured, somewhat granulose at base, and raised into asperate tubercles 
at apex ; apex of second interstice depressed and without tubercles ; legs black, 
tarsi red. Length 3-J-4 mm. 
M. minor Hart (fig. l). — Very like the preceding, but on the average a little 
smaller (although according to Thomson it is of the same size), with the strise of 
the elytra finer and more finely punctured, and - the interstices more closely 
punctured, the second not being depressed and being furnished with a series of 
small tubercles on its apical declivity. It is also distinguished by the fact that of 
the teeth on the hind. tibiae one is situated about the centre of the tibiae ; the same 
tooth in piniperda is past the centre ; the elytra are usually brownish red. Length 
3^— 3f mm. 
In Fowler’s description of M. minor no special mention is made of the shape 
of the prothorax. In what might be described as typical specimens the prothorax 
is cone-shaped and has a smooth middle line (fig. 2). In many specimens of 
M. minor, however, in the proportion perhaps of 1 to 30, there is a distinct 
variety where the shape of the prothorax differs from the above. In this variety 
the prothorax is markedly narrowed in front and has a distinct elevation along 
the middle line (fig. 3). 
Further, while on the whole this is a slightly smaller species than M. piniperda, 
as its name minor indicates, yet I found not rarely specimens slightly exceeding 
Fowler’s figures. 
In the table which follows I contrast in two columns these two beetles, emphasis- 
ing characters which have proved most helpful in my work with them. 
M. minor. 
M. piniperda. 
Size ...... 
3'5 mm. - 4’5 mm. 
3 '5 mm. - 5 mm. 
Elytra of mature beetles . 
Reddish brown 
Black, sometimes dark reddish 
brown 
Apex of second interstice of 
Bears a row of tubercles and is 
Bears no tubercles and is hollowed 
elytra 
not hollowed out (fig. 4) 
out (fig. 5) 
Posterior tibiae . . . . 
Tooth about centre (fig. 6) 
Tooth past centre (fig. 7) 
A rough-and-ready character which often proved useful to me in distinguishing 
the one species from the other is that, owing to the finer nature and hence 
greater transparency of the elytra of M, minor , the dorsal portion of the third 
