192 RHYNCHOPHORA. 
the dwarfed and subapterous condition of the comparatively rare males. The Xylebori, 
together with the other components of Eichhoff’s section Xylophagi, and the Platy- 
podides constitute the so-called ‘“‘ambrosia” beetles. Burrowing deeply into wood of 
various kinds, they are nevertheless not true wood-feeders, either in the larval or imago: 
stage, but subsist on certain minute fungi that grow in the galleries and produce the 
black coloration which is diagnostic of the burrows of this biological group. The 
habits of all these insects have lately been thoroughly investigated and the results 
published in a remarkable and highly interesting paper by Mr. H. G. Hubbard (“The 
Ambrosia Beetles of the United States,” U.S. Dept. of Agriculture, Bull. no. 7, new 
series, 1897). 
According to Mr. Hubbard, the perfect insects tend their young in a manner utterly 
foreign to most Coleoptera, and akin to that of the social Hymenoptera and Neuroptera ; 
the latvee themselves manifest a considerable amount of intelligence, and are able to: 
show fight for the protection of their younger brethren. The ambrosial fungus does. 
not grow at random, but is started by the mother on a carefully prepared bed, and the 
excrement of the larve is also used to form new propagating-beds or layers. A 
certain amount of moisture in the wood is necessary for the growth of the fungus, and, 
unlike Anobiide, these Scolytids never by any chance propagate in dry and seasoned 
timber, usually attacking sickly, dying, or recently dead trees in which the sap has 
begun to ferment. A few species, however, are known to infest wine- or beer-casks in 
which the necessary condition of the wood has been artificially produced, and these 
may cause enormous damage, as has happened in India. 
A third genus of this subgroup, Premnobius, Eichh., is likely to occur in Central 
America. The single described species, P. cavipennis, Kichh., is recorded, singularly 
enough, from the Cape of Good Hope and Colombia. I have an example of it and 
two or three of a larger undescribed species from tobacco, possibly Mexican. 
The two known Central-American genera may be separated as follows :— 
Tibize straight, widened apically, truncate at the apex ; prothorax uniformly convex, 
nearly uniformly scabrous with small asperities, obsoletely margined at the 
base; body subovate 2... 6 ee ee ee ee, Coccotrypes. 
Tibize compressed, dilated towards the apex, their superior border rounded ; prothorax 
not bordered at the base, usually declivous in front, with a more or less distinct 
median gibbosity, rarely granulate or asperate behind the middle ; body usually 
cylindrical . - Xyleborus. 
COCCOTRYPES. 
Dryocetes, Eichhoff, Berl. ent. Zeitschr. 1864, p. 38 (pars). 
Anisandrus, Ferrari, Borkenk. p. 24 (pars). 
Coccotrypes, Eichhoff, Rat. Tom. p. 314. 
The species of this genus consist of a small number of closely allied forms which: 
