DESCRIPTIONS OF GENERA AND SPECIES. 195 



are the principal characteristic of the genus. The two 

 anterior differ greatly from the two posterior pairs. 

 The former are extremely narrow from side to side, so 

 that they look almost linear when seen on edge ; but 

 they are deep dorso-ventrally, so that they look broad 

 when seen from the side. The whole of each tarsus of 

 these two pairs of legs diminishes gradually, and forms 

 a great curved, but not hooked, claw : it is with this 

 tarsus used as a claw that the creature climbs and holds 

 on. It is a powerful holding organ ; a similar develop- 

 ment of the tarsus into a holding claw may be found 

 in the enlarged leg of the heteromorphic males of 

 RMzoglyphus, but there the true claw is entirely absent. 

 In Lentwigula a long flexible peduncle arises from the 

 side of the tarsus about halfway between the proximal 

 and distal ends ; this peduncle ends distally in a small 

 bulb, which bears a minute claw. Every part of the 

 peduncle can be flexed in any direction at the will of 

 the creature ; the bulb with its claw can also be turned 

 in any direction, but cannot be bent in the middle. 

 This claw and peduncle are not used in climbing or 

 holding as far as I could see, and I observed them 

 carefully in life. The peduncle is usually flexed up- 

 ward when the creature is climbing, so as to keep the 

 small claw out of harm's way ; it seemed to me to be 

 used more as a tactile than a holding or climbing organ. 

 The two posterior pairs of legs are quite different ; 

 they are thin rounded legs of the ordinary type ; their 

 tarsi are terminated by large claws without peduncles, 

 and also without suckers or caruncles. 



Ventral Surface, The chitinous skeletal pieces are 

 very well developed, particularly the sternum. The 

 external genital openings are placed between the coxse 

 of the third and fourth pairs of legs in both sexes, and 

 are protected by band-like sclerites. The anus is ter- 

 minal; formed of two blades on edge lying close 

 against each other; they form a small point in the 

 centre of the posterior margin, but the opening is ventral. 



Immature Stages, These greatly resemble the adults, 



