Abdomen club-shaped, anteriorly produced into a very long, thin, cylindrical process, which is twice bent, so that its basal half is leaning backwards on the back of the abdomen, whilst its terminal half is directed upwards and forwards, terminating in a slight cuneiform swelling: this singular appendage is covered with a leathery, fine hairy skin, like the lower parts of the abdomen. The cephalothorax being united with the abdomen at no great distance from the spinners, the anterior portion of the abdomen, with its appendage, is situated vertically above the thorax. The abdomen is nearly smooth above, and covered with very fine hairs below; it terminates in an obtuse point directed upwards. Six spinners in a quadrangular group immediately before the vent: the anterior and posterior pair are of moderate size: the third pair is very short, and situated between the posterior spinners. Two branchial opercula: tracheal opercula absent. _Dimensions._ Lines. Length of cephalothorax 4 „ abdomen to the first bend of the appendage 12 „ appendage from its first bend 10 „ falces 1-1/3 „ palpus 4-1/3 „ terminal joint of palpus 1-2/3 „ first leg 16 „ second leg 16- /3 „ third leg 9 „ fourth leg 10-1/2 Colour brownish yellow: extremities of the legs and of abdominal appendage and sternum blackish brown: upper parts of the abdomen yellow: two black bands round the femur of the first leg. A single female specimen of this spider was obtained by the late M. Mouhot in the Lao Mountains of Cochin China. Its form is so extraordinary that we have not hesitated to refer it to a new genus, _Cyphagogus_. DESCRIPTION BY M. LE COMTE DE CASTELNAU OF A NEW AND GIGANTIC CARABIDEOUS INSECT DISCOVERED BY M. MOUHOT IN LAOS. (Communicated by the Count to the ‘Revue et Magasin de Zoologie.’ 1862. No. 8. Paris.) GIGANTIC CARABUS. Among the magnificent insects that M. Mouhot collected during the few months of his stay in Laos, the first place is claimed by the beautiful Carabus which forms the subject of this paper, and which I have named _Mouhotia gloriosa_ after my unfortunate countryman. This splendid insect is black, with a large border of flame-colour at the sides of the thorax and of the elytra; this is covered with longitudinal striæ, formed by a double row of punctures. The thorax is hollowed behind, smooth on the top, with the lateral border a brilliant coppery-red; it presents a small longitudinal stria in the middle of its disk, and the anterior angles are very prominent.