REPORT ON THE CRUSTACEA MACRURA. 169 



extremity terminating in an obtuse apex. That of the male (PI. XIX. p) is also uni- 

 branehed and biarticulate. The first joint is subcylindrical ; the second is subcylindrical 

 at the base, but gradually widens into a broad and thin spatuliform plate, that is 

 strengthened by a rib longitudinally traversing the centre. 



The second pair of pleopoda (q) is biarticulate ; the first joint is long, the second 

 biramose, and the inner branch carries a single stylamblys in the female and two in the 

 male on the anterior pair, and one on each of the three following, on all of which a group 

 of cincinnuli exists at the apex in both sexes, while the margins are fringed with a row of 

 ciliated hairs particularly on the outer side. The posterior pair of pleopoda and the telson 

 form a powerful and well-developed rhipidura, the outer rami of which are broad and 

 rounded at the extremity, bear a tooth on the outer margin, and are strengthened with 

 a longitudinal median rib, as also is the internal plate. The telson is triangular and 

 pointed. 



Observations. — A female which I have used for this description was taken in the 

 middle of the North Atlantic Ocean, half-way between the western coast of Africa and 

 the West Indies. A second was taken in the middle of the South Atlantic, near Tristan 

 da Cunha, about the latitude of the Cape of Good Hope and Buenos Ayres ; and a male 

 of the same species was taken near the island of Juan Fernandez, off the south-western 

 coast of South America, in the same latitude as that which was captured near Tristan 

 da Cunha. With this last specimen were also taken a species of Pentacheles and a very 

 fine male specimen (PI. XIX. c) of a decided variety of Willemcesia leptodactyla. It 

 is larger than the female of the type specimen, being quite 4 - 5 inches in length, and thus 

 half an inch longer than the largest female taken, and 1*5 inch longer than the only other 

 male captured, and which was taken in the same locality. The dorsal surface, instead of 

 being granulated and furry, is covered with numerous small sharp points or denticles, that 

 are most numerous and closely packed on the anterior half of the carapace, but larger 

 and more important on the posterior. All the teeth on the carapace are more con- 

 spicuous, and there are ten on the anterior division of the lateral margin, eight on the 

 middle, and twenty-four on the posterior. The frontal margin is more advanced, and 

 the internal orbital angle armed with more conspicuous teeth. The median crest, 

 formed by the approximation of the upturned inner margins of the scale-like pro- 

 cesses of the first pair of antennae, is armed w T ith longer and more conspicuous teeth, 

 and the hairs that fringe it in the type-specimen are wanting. In all other respects it 

 agrees with the typical form, except, perhaps, in having the telson longer and more 

 pointed, and the outer foliaceous plates of the rhipidura somewhat pointed at the 

 extremity. 



One of the specimens was taken about 130 mdes distant from the coast of South 

 America, off Valparaiso. It carried a great number of ova attached to its pleopoda, in 

 a somewhat advanced stage of embryonic development; a circumstance that enabled 



(ZOOL. CHALL. EXP. PART UI. — 1SS6.) Fff -2 



