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NACERDES.—DITYLUS. 117 
Nacerdes, like Xanthochroa, has twelve-jointed antenne in the male, a single spur to 
the anterior tibia, and bifid mandibles. We have only to notice a single species from 
our region, and this an introduced one from Europe, which seems to be rapidly 
extending to various parts of North and Central America. This species, V. melanura 
(Linn.), though a common insect on the sea-shore, where it breeds in old posts &c., is 
frequently found inland; it has no doubt been transmitted in timber. 
1. Nacerdes melanura. 
Cantharis melanura, Linn. Faun. Suec. p. 205; Hamilton, Cat. of Col. common to N. America, 
Northern Asia, and Europe, in Trans. Am. Ent. Soc. xvi. pp. 152, 153 (1889)"*. 
CGidemera apicalis, Say, Bost. Journ. Nat. Hist. i. p. 188°; Complete Writings, i. p. 660. 
Hab. Norta America, Nova Scotia!, Pennsylvania?, Ohio}, Kansas!, Louisiana ”, 
California !.— Mexico, Yucatan (Horn); Costa Rica (Van Patten). — Europ: ; 
NoRTHERN ASIA. 
DITYLUS. 
Ditylus, Fischer, Mém. Soc. Imp. Nat. Mose. v. p. 469 (1817); Lacordaire, Gen. Col. v. p. 703 ; 
Leconte & Horn, Class. Col. N. Am. p. 404 (1883). 
Mimetes, Eschscholtz, Mém. Ac. Petr. vi. p. 468 (1818). 
Species of this genus have been described from Europe, East Africa, Madagascar, 
North America, and the Canary, Salvages, and Cape Verd Islands. Six are here 
enumerated from Central America, one from Mexico and five from the Los Altos 
region of Guatemala; several of these differ widely from the known species of the 
genus in the enormously enlarged head in fully-developed males, this development 
being also present to a less degree in the female. Every degree of development is 
present in the Central-American species, from that of the European D. levis (Fabr.), 
in which the head is not at all dilated behind the eyes, to one in which the head in 
the male is almost as large in proportion as it is in the same sex of the genus Horia. 
In the lowest development of the.female of D. meaxicanus the head is formed as in 
D. levis and various North-American forms; in most of our examples of the various 
species, however, not only of the male but of the female also, the head is more or less 
dilated at the sides behind the eyes, and in this respect the Central-American repre- 
sentatives of the genus apparently differ from all others yet described. 
In these latter the antenne are stout in both sexes, and about reach the middle of 
the elytra (in the females of D. brachinoides and D. cephalotes they are shorter); the 
eyes are small and distant from the point of insertion of the antenne, finely granulated, 
rather transverse, and usually prominent; the mandibles are bifid; the joints 1-4 or 
2-4 of the front tarsi, 1-4, 2-4, or 3 and 4 of the middle tarsi, and 3 of the hind tarsi 
are spongy-pubescent beneath; the tibial spurs are long; and the claws are simple. 
The three insular species described by Wollaston have larger, more depressed, and 
