88 THE VOYAGE OF H.M.S. CHALLENGER. 



its upper margin bears two irregular compound teeth, in addition to some small tufts of 

 setse ; the dactylus has its upper surface granular, and like the immobile finger is slightly 

 incurved, its lower margin bears two compound teeth and numerous tufts of setas. The 

 left chelipede is slender and the joints are comparatively smooth, though the inner border 

 of the carpus is raised and tubercular, and its lower surface is densely pubescent ; 

 the dactylus is equal to more than half the total length of the propodus, whereas that of 

 the right chelipede is less than half the length. The ambulatory limbs are remarkably 

 long and slender, the extreme tenuity of the dactyli being a special feature ; the second 

 exceeds the first by about half the length of its dactylus ; the meral, carpal, and propodal 

 joints have their anterior, and to a certain extent their lateral surfaces granular ; the 

 dactyli are comparatively smooth and slightly tortuous, with the apex acute, they are 

 also obscurely canaliculate, their length appears to vary considerably in difi'erent specimens, 

 and in certain adult males may equal that of the body. The ultimate and penultimate 

 pairs of legs have their borders fringed with delicate hairs. 



The penultimate abdominal segment bears a cruciform impression ; the terminal 

 segment is composed of a single lobe with a sinuous margin. 



The above description is furnished by an adult male taken at Station 300, which 

 gives the following measurements : — liCngth of body 50 mm., of right chelipede 73 mm., 

 of left chelipede 55 mm., of thii-d right leg 140 mm., of dactylus of same leg 49 mm., of 

 ocular peduncle 6 mm. 



A certain amount of variation is noticeable in specimens from different locahties, more 

 especially as regards the amount of pubescence and granulation on the chelipedes and 

 ambulatory limbs. In a specimen from Station 133, the ophthalmic scales are bidentate, 

 and the external prolongation of the second antennal peduncular joint is dentate. In 

 spite of these apparent incongruities, an examination of the numerous specimens taken 

 by the Challenger has convinced me that they all belong to a single species. Females 

 are of much smaller size than males, indeed one with ova from Station 300 (where the 

 largest males occurred) measures only 29 mm. in length ; in females also, the immobile 

 finger of the right chela is bent at a more obtuse angle to the hand than in males. 



Parapagurus abyssorum is of special interest on account of its very extended 

 distribution and deep-water habitat. It was taken by the Challenger in all the great 

 ocean beds explored (with the exception of the Southern Ocean between the Cape and 

 Austraha), and nowhere in less than 1000 fathoms of water. It appears to be invariably 

 associated with an Anemone which exerts a solvent action on the Gastropod shell 

 originally selected as a dwelling-place by the Hermit; in many cases the shell has entirely 

 disappeared, and in others it is greatly reduced, while the Anemone forms a soft and 

 saccular covering on the exterior. The "Tahsman" collection at Paris contains examples 

 of this species, named Pagurus aJjyssorum by Professor A. Milne-Edwards ; I have 

 therefore in the above description adopted his specific name. In Parapagui'us pilosi- 



