Mr. H. W. Bates on the Longicorns of the Amazons Valley. 31 
posterior pair of pleopoda must be very effective organs also, by 
the leverage that may be attained through them for assisting 
the animal to turn easily in its narrow cave. 
EXPLANATION OF PLATE II. 
Fig. 1. Caradina tenuis: 1", rostrum. 
Fig. 2", Caradina varians, rostrum ; 2 h, first pair of pereiopoda. 
Fig. 3¢. Palinurus vulgaris, second pair of antenne ; c*, scaphocerite. 
Fig. 4. Spheroma vastator: c, cephalon; 6, superior antenna; c, inferior 
antenna; d, mandible; d’, mandibular appendage; f, second 
siagonopod ; g, third siagonopod; h, 2, gnathopoda; &, first pair 
of pereiopoda; /, second pair; m, third pair; 2, o, fourth and fifth 
pairs; p, 4,7, first three pairs of pleopoda; s, fourth pair; ¢, fifth 
pair ; v, posterior pair of pleopoda. 
Fig. 5. Spheroma terebrans (Fr. Miiller): d", mandibular appendage ; 
v, posterior pair of pleopoda. 
I1I.—Contributions to an Insect Fauna of the Amazons Valley. 
CoLtrorrers: Lonercornes. By H.W. Barus, Esq. 
[Continued from vol. xvi. p. 314.] 
Genus Cacosto1a (Dej. Cat.), Fairmaire. 
Fairm. Aun. Soc. Ent. Fr. (1859), p. 532. 
This genus, imperfectly characterized by M. Fairmaire, com- 
prises a number of small-sized lmear msects, closely allied to 
Hesycha and Trestonia, but distinguished by their narrow forms, 
obscure coloration, and especially by their much shorter heads, 
the muzzle being very little prolonged beyond the lower margin 
of the eyes. The antenne are moderately distant at their bases, 
their supporting tubercles having a conical projection on their 
inner sides; they are slender, filiform, naked, and very little 
longer than the body; their first jomt forms a smooth club, 
their third jomt is m some species curved, and their terminal 
joint is at least as long as the preceding. The thorax is short 
and cylindrical, with a scarcely perceptible prominence in the 
middle of each side, and the surface punctured, not wrinkled 
transversely. The elytra are linear, obtusely rounded at their 
apices, and their surface is free from ridges and tubercles. The 
legs are short, the thighs clavate, and the claw-joint of the tarsi 
longer than the remainder taken together. The sterna are 
narrow, the pro- and mesosterna of equal width, and simple. 
The species are found, like the Trestonie, clinging to slender 
decaying branches of trees. 
1. Cacostola simplex, Pascoe. 
Pachypeza simplex, Pascoe, Trans. Ent. Soc. n.s.v. pt. 1. p. 44. 
C. linearis, griseo-fusca; thorace elytrorumque lateribus grisco 
