ABERRANT WOOD-BEETLES. 
101 
Tuibe X. 
ABERRANT WOOD-BEETLES. 
Lignivora aberrantia. 
Under the title of aberrant or exceptional Wood-beetles, as stated in 
the general remarks upon the Serricornes, we have included, for the 
sake of brevity and convenience, a number of small families, some of 
which have but a remote relationship to the others, but which cannot 
naturally be united with any of the larger tribes. 
This tribe contains two very dissimilar groups. In the first, which is 
composed of the family of Ptinidae, including the sub-family of Bostri- 
chides, the body is rather short and thick, or moderately elongated and 
cylindrical, and the head is bent down and mostly or wholly concealed 
under the vaulted or hood-like thorax. 
In the other group, which includes the small families of Lymexylo- 
nidie, Oupesid® and Lyctidie, the body is much elongated and ofteu 
depressed, and the head is free and exposed, and sometimes attached 
to the thorax by a short neck. These three families combined do not 
contain more than a dozen known American species, most of which are 
rare, and are found mostly under the bark of decaying trees. Many 
authors include them in some one or other of the larger families. 
[Fiff. 40.] 
Family XXXVI. PTINID/F. 
This is a. family of moderate extent, composed of small insects, rarely 
exceeding a quarter of an inch in length, and often only about half that 
length, and usually of a cinnamon-brown color, sometimes black and some- 
times oi’uameuted with patches 
of whitish scales. Their most 
distinctive character is the vault- 
ed or hood-like form of the ante- 
rior part of the thorax, the head 
being bent under it or partly re- 
tracted within it, so that it can 
be scarcely or not at all seen 
when the insect is viewed from 
above. The antennae are gener- 
ally filiform, but in Bostrichus 
a, Anoiiium panicbum, Fab. : b, ita antenna) ; o, Pi'i- . _ 
nub BuuNNBus, Dufs.— after Riley. they terminate in three larger 
joints. The tarsi are simple. The larvae resemble those of the Lamelli- 
corn beetles, in miniature, being soft and white, and usually lying in a 
curved or semi circular position. They have six legs, but do not use 
them in crawling in the usual way, but draw themselves along upon 
their sides. 
