120 Mr. K. I. Pocock on the 



conceal the rather strong and closely placed punctures. An- 

 tennas rather slender, sparsely ciliate underneath, dark brown, 

 with the fourth and fifth joints and proximal half of sixth 

 testaceous ; the third joint, which is also very narrowly testa- 

 ceous at the base, is about equal in length to the first and 

 second taken together and is a little longer than the fourth. 

 The last two abdominal segments are covered with a dense 

 pale yellow pubescence, the rest of the underside being of a 

 fuscous or dark reddish colour. The coxse and femora are 

 pale testaceous, the tibiae and tarsi dark brown. 



This species has a close superficial resemblance to Isomerida 

 picticorm's, Bates, but may be distinguished, inter alia, by 

 the slenderer appearance of the antennas, which are only 

 sparsely ciliated and without the thick fringe which is present 

 on the basal joints of the latter species. 



The resemblances that hold between different species, even 

 of distinct genera, in this group seem to be accounted for by 

 their common mimicry of some forms of Lampyridas and 

 other Malacoderms. 



XXI. — Notes on the Thelyphonidas contained in the Collection 

 of the British Museum. By R. I. POCOCK, of the British 

 Museum (Natural History). 



[Plate II.] 



Synopsis of the Genera of Thelyphonidae. 



a. The anal segment without ommatoids; the 



carapace angularly pointed in front and 

 not furnished either with cephalic keels 

 or with a ridge between the median eyes. Thelyphonellus, g. nov. 



Type amazonicus (Butl.). 



b. The anal segment bearing one or two om- 



matoids on each side ; carapace bluntly 



rounded in front. 



a 1 . Carapace not furnished on each side 



with a keel running forward from the 



lateral eyes ; no distinct ridge between 



the median eyes. 



a 2 . Coxal apophysis of the chela with a 



distinct spine on its inner edge (cf. 



also secondary sexual characters of 



male) Labochirus, g. nov. 



TyTpeproboscideus(Butl.). 

 b 2 . Coxal apophysis of chela unarmed 

 (cf. secondary sexual characters of 



male) Hypoctonus, Thorell. 



Type formotsus (Butl.). 



