190 Dr. E. L. Trouessart — Synoptical Revision 



epistome, of which the anterior margin, cut squarely and a 

 little rounded, advances as far as half the length of the 

 second joint of the palpi. Inward spine of third joint very 

 slender. Claws pectinate except the first pair ; tooth of the 

 median piece appearing to be inserted beneath the tarsus in 

 the form of a short spine (except in the first pair, where it is 

 in its normal position, as in A. hirsuta). Plates of the 

 cuirass finely punctured, leaving little space between them. 

 Total length 0-68 millim. 



Hab. Shores of Tierra del Fuego, Cape Horn (Hariot), 

 upon Alga3 (Ceramium Dozii). 



Genus Scaptognathus, gen. nov. 



Char. Rostrum large, separated from the body by a well- 

 marked constriction, pyriform as in the genus Leptognathus. 

 Palpi very stout, arranged laterally, widely separated from 

 each other, and constructed to act horizontally one opposite to 

 the other ; second joint very long and very stout, armed at its 

 extremity with a strong double spine directed inwards ; third 

 joint null or very small ; fourth bent downwards, very 

 slender, styliform. Epistome very short or null, leaving the 

 rostrum exposed. Hypostome very long, attaining the ex- 

 tremity of the second joint of the palpi, strongly spatuliform. 

 Mandibles very long and very slender, with the point straight 

 styliform. 



Only one species known. Notwithstanding the resemblance 

 presented by this type in the general form of the rostrum to 

 the genus Leptognathus, it differs therefrom essentially in the 

 structure of the parts of the mouth. The palpi, with the 

 second joint very robust and furnished with an inwardly- 

 directed fork at its extremity, constitute organs of prehension 

 evidently intended to act in the horizontal and not vertical 

 direction. On the other hand the very slender mandibles can 

 act only in an antero-posterior direction by sliding in the 

 groove of the hypostome. 



1. Scaptognathus tridens, sp. n. 



Char. Rostrum very large, nearly as long as the body • 

 second joint of the palpi in the form of a cubitus, of which 

 the olecranon would represent the anterior extremity outwards; 

 this extremity furnished within with a strong forked spine in 

 the form of a mattock, forming, with the slender and pointed 

 last joint, which is bent downwards, a sort of trident. Hypo- 

 stome transparent, dilated in front in the form of a T. Legs all 



