OCR Text |
Show 1869.] DR. A. M A C A L I S T E R O N G Y R O P U S D I C O T Y L IS. 421 concave, and the posterior convex, the apex of the lobe being directed forwards and outwards. This appearance is similar to the arrangement of these lobes in G. ovalis of the Guinea-pig. Frontal margin convex, obtuse, fringed by a few hairs ; eye very small, inconspicuous, situated in front of the temporal sinus on the upper surface of a Gyropus dicotylis (magnified). small eminence, and guarded by a few hairs. Occipital margin convex on either side, slightly concave in the centre, but not nearly so much as in G. ovalis. The antennse have their basal joints cylindrical, large, the second short and rounded, the third club-shaped, the fourth and last is large and dilated, bent upwards and backwards ; these joints are well defined, and each one begins extremely narrow. In G. ovalis the last joint is securiform ; in the present species it is more club-shaped. The maxillary palpi are four-jointed, each joint being more slender than its precessor, the terminal segment being the smallest, and the third the longest. The neck is one-third the breadth of the head (one-half in G. ovalis). Prothorax hexagonal, flattened, wider transversely than antero-posteriorly, smaller than the head ; this segment is longer than the head in G. lonyicollis of the Agouti, but it is equal to it in G. hispidus (the parasite of the Three-toed Sloth). There is no trace of the transverse depressed line on the prothorax, which is characteristic of G. ovalis. Sternum slightly prominent. The union between the prothorax and the combined meso- and metathorax is of the same size as the neck. This compound segment is quadrilateral, wider behind than in front, and bearing the two posterior pair of legs, between which opens, on each side, a spiracle. It is once and a half the length of the prothorax, and very slightly wider. The first pair of limbs are *05" long, with a single incurved unguis. The tibia is armed at the junction of its middle and lower third with a prominent tooth, which PROC. ZOOL. Soc-1869, No. XXVIII. |