— 40— 



orifice in the terminal mandibular claw, which would occur here as well 

 .is in all other Arachnida which have a poison gland in their mandibles. 

 But they have another weapon, useful only for defense; for they can 

 emit a sharp and penetrating odor very much like acetic acid. The in- 

 habitants of some West India Islands therefore call them "Vinaigrier" or 

 vinegar maker. Where that odor gland is situated in the body of 

 Thelyphonus I am unable to say as my studies were confined only to 

 dried specimens. 



EXPLANATION OF PLATE. 



Fig. i. Thelyphonus giganteus Latr. 



male (Thel. excubitor Girard). 



Fig. 2. Thelyphonus giganteus Latr. 



female. 



Fig. 3. Sternal surface of the female. 



Fig. 4. Lateral eye eminence with the 

 five eyes. 



Fig. 5. Front showing the mandibles. 

 All the mouthparts are hidden 

 under a thick pubescence and 

 these hairs have been removed 



to show the mandibles and 



maxillae. 

 Fig. 6. Front from the side. 

 Fig. 7. Abdomen of the male, showing 



the sexual orifice. 

 Fig. 8. Themandiblesseparated.afrom 



the inner side; b. from the outer 



side, 

 tig. 9. On organ of special sense, situ 



ated at the tibia of each lear. 



Remarks on North American Scolytids. 

 By E. A. Schwarz, Washington, D.C. 



Gnathotrichus materiarius. Dr. Packard in his Guide, p. 493, 

 (see also Bull. 7, U.S. Ent. Comm., p. 174) states that "a species, prob- 

 ably the Cryphalus materiarius of Fitch" has been found to bore into 

 empty wine casks and spoil them for use. This is undoubtedly a con- 

 fusion of species, as G. materiarius lives exclusively in pine trees. The 

 species in question was probably Xyleborus fuscatus which, in my ex- 

 perience, bores in several kinds of deciduous trees. 



Gnathotrichus asperulus is perhaps not rare; but not easily 

 recognized. It bears a close resemblance to the smaller and rubbed 

 specimens of Pityopldhorus miiiuiissimus, from which it differs mainly by 

 vestiture of the antennal club. I beat two specimens from Pinus inops 

 near Washington in May. In this tree it will probably be found boring 

 in the same manner as G. materiarius. 



Pityophthorus. The first group of this genus (Leconte's group 

 B), at once recognizable by the fine and dense punctuation of the elytra, 

 includes a few easily distinguished species, infesting deciduous trees. 

 The sexual differences seem to be alike in all species. The second group 

 (Leconte's group C), divides naturally into two sections: In the first the 

 elytra] declivity is dissimilar in the two sexes. The three species which 



