RHACIUS. 121 
been drawn up to receive two undescribed species, the Tenebrio sulcatulus, Dej., and 
the Calcar quadricollis, Laferté, from Central and South America. Rhacius may be at 
once known from the Old World genus Calcar by the very distinctly margined thorax 
and elytra, the thorax scarcely narrowed at the base, the shorter antenne, toothed 
femora, &c.; the head is formed much as in a species of Calcar (C. procerus, Muls.), 
separated by Mulsant from that genus under the name of Centorus. The absence (as 
in Calcar) of the distinct coriaceous hind margin to the third and fourth ventral 
segments makes the genus difficult to locate satisfactorily ; the general form of one of 
the species is similar to the North-American Tenebrio castaneus, Knoch (separated, 
and in the writer’s opinion rightly, as generically distinct from Tenebrio in Mr. F. Bates’s 
collection). Allied more distantly to Bius, Muls.; in both these genera, however, the 
hind margins of the third and fourth ventral segments are distinctly coriaceous. In all 
the specimens before me, consisting apparently of both sexes, the four hinder femora 
are strongly toothed. 
Both species have been beaten from herbage. 
1. Rhacius sulcatulus. (Tab. VI. fig. 9.) 
Tenebrio sulcatulus, De}. Cat. p. 226. 
? Tenebrio opatroides, Perty, in litt. 
Elongate, parallel, moderately convex, dark reddish brown or black, dull, slightly pubescent. Head closely 
and rugulosely punctured, the epistoma separated from the front by a deep transverse impression ; pro- 
thorax scarcely broader than long, subquadrate, feebly rounded at the sides, widest about the middle, 
almost equally narrowed at the base and apex, broadly but not deeply emarginate in front, base feebly 
bisinuate and almost straight, hind angles rectangular, very closely, finely, and rugulosely punctured, with 
a smooth central line, and the disc shallowly impressed before the base ; elytra about twice as long as. 
and but little wider than the prothorax, sides subparallel and narrowing very gradually from the base, the 
apex broadly rounded, base nearly straight, humeri distinct, punctate-sulcate, the punctures muricate, 
transverse, and closely placed, interstices narrow, convex, .almost smooth (finely and very sparingly 
punctured) and shining. The entire surface beneath closely and finely punctured ; legs reddish brown ; 
prosternum truncate at apex. 4 
Length 8-10 millim. 
Hab. Mexico, Vera Cruz, Playa Vicente (Sallé), Oaxaca (Hage), Yucatan (coll. 
F. Bates) ; Guatemaua, El Reposo, San Gerénimo (Champion) ; Nicaracua, Chontales 
(Janson).—SouTH AMERICA, Carthagena; Wesr Inptus, Cuba. 
Many examples. 
9. Rhacius quadricollis. (Tab. VI. fig. 10.) 
Calcar quadricollis, Laferté, in litt. 
Elongate, parallel, feebly convex, flattened above, black, shining, glabrous. Head closely, finely, and equally 
punctured, the epistoma confounded with the front; prothorax quadrate, as long as broad, sides almost 
nt, and narrowing very slightly towards the base, slightly convex anteriorly, hind 
straight, widest in fro : : 
angles rectangular, very closely, finely, and equally punctured, the base with a short, shallow, oblique 
impression on each side about the middle ; elytra twice as long as and but little wider than the prothorax 
at the base, sides almost straight, closely punctate-striate, the interstices flat and sparingly and finely 
BIOL. CENTR.-AMER., Coleopt., Vol. IV. Pt. 1, October 1885. RR 
