REPORT ON THE ANOMURA. 107 



merus is proJuced into a rounded tooth ; tlie carpus is about equal iu length to the hand, 

 and slightly more than half the length of the caraiDace, its anterior border bears a single 

 lobe of small size (hence the specific name) near the proximal end, the posterior border is 

 raised, and the surface immediately behind is marked by numerous slight vertical rugosities, 

 a faint median elevation runs along the upper surface of the joint, and the border over- 

 hanging the insertion of the propodus bears four unequal teeth ; the propodus is narrow 

 proximallv but dilates somewhat towards its distal end, the anterior margin is raised and 

 has a doul)le outline, while a median elevation runs along the upper surface, in some 

 specimens there is a small rounded lobe on the under surfoce fitting into a depression 

 at the end of the merus ; the fingers are somewhat curved, with their apices subacute 

 and bent, the tip of the dactylus being folded under that of the immobile finger. The 

 ambulatory limbs are comparatively smooth, a few slight transverse lines being present 

 on the meral joints, and the carpi have their upper surface faintly carinated ; the dactyli 

 are acute and curved, with a few horny spines on their posterior margin ; a few hairs and 

 minute horny spinules are also present on the posterior margin of the projiodi. 



The abdominal segments are smooth and polished externally. 



Breadth of carapace of a male 6 mm., length of carapace 7 mm., of extended abdomen 

 5"5 mm., of chelipede 12 mm., of third ambulatory leg 8 mm. The female is apparently 

 of much smaller size. 



This species is allied to Petrolisihes japonicus (De Haan), and Petrolisthes elongatus 

 (Milne-Edwards). In the former the chelipedes are longer, and the cai^pus is equal in 

 length to the carapace, with one or two teeth on its inner border, and two on the outer 

 border. In Petrolisthes elongatus the outer border of the carj)us is armed with from 

 two to three teeth. 



Habitat. — Station 172, off Nukalofa, Tongatabu ; depth, 18 fathoms; bottom, coral 

 mud. Two males and two females, the latter with ova. 



Petrolisthes senxttus, n. sp. (PL XI. fig. 2). 



Characters. — The carapace is ovate and smooth, with numerous short transverse lines 

 most conspicuous on the branchial and gastric areas, a few slight granulations are also 

 present on the mid-branchial and frontal regions. The front is broad and slightly 

 depressed, with the margin faintly crenated, and the apex rounded ; a small fissure is 

 present opposite the anterior border of the eye-stalk, bounded posteriorly by a short 

 acute tooth. A small slightly convex lobe is placed between the antero-lateral angle and 

 the point where the cervical groove passes on to the carapace, immediately behind this 

 the lateral border commences in an acute spinule, and a slight carina is continued backwards 

 for some distance but loses itself opposite the mid-branchial area ; the postero-lateral 

 border is not sharply defined, being represented simply by a rounded surface. The posterior 



