PYCNOGONIDA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 153 



Oviger ten-jointed ; denticulate spines few, with four teeth on each side, two of them 



prominent. 

 Legs with five rows of spinous setae, without enlarged bases ; terminal claw with two 



small auxiliaries. 



I have fully described this species in the Report quoted above. Its occurrence on 

 the opposite side of the Polar area is a matter of great interest. No less than thirteen 

 specimens of both sexes were found among an immense number of Chastonymphon 

 oroadenne from Scotia Bay, taken in depths of less than 15 fathoms. As in the case 

 of those taken by the Discovery, the body is quite smooth, and while there is a fair 

 amount of variation in the setose covering of the appendages, its arrangement is 

 characteristic. The lateral processes carry two stout spines dorsally and distally ; but 

 the number is not confined to two. Two other smaller ones may be found outside the 

 principal ones. The spinous armature of the coxse varies more, and while the setae on 

 the femur are not so regular in their distribution, the characteristic five rows of strong 

 setae are conspicuous on the tibiae, the two dorsal rows having the smaller setae. One 

 specimen the largest, and an adult female has its setose covering the least well 

 developed. 



The Ocular tubercle of all these specimens is rather flattened and tapering from a 

 broad base. 



The Denticulate spines, which in the type specimens were rather worn, are here well 

 preserved. The large female already alluded to has the same number as the type ; the 

 males may have fewer. 



The shaft tapers, and may have as many as five lateral teeth, the fifth being little 

 more than a trace. 



Chsetonymphon orcadense (Plate II., figs. 2, 2a). 



Specific Characters. Body robust, with lateral processes close together, setose. 

 Palps five-jointed; proportions of three terminal joints 4, 2'5, 2'5. 

 Oviger ten -jointed ; denticulate spines rather numerous, with 5-7 lateral teeth. 

 Legs coarsely setose, with terminal claw and well-developed auxiliaries. 



Body robust, with lateral processes of unequal length, giving it an ovoid form ; they 

 are distinctly though not widely separated, variable, apparently depending on age. 

 Segmentation is very distinct. 



The Cephalon is not long, constricted near the middle to form a distinct neck, and 

 then widely expanded, forming two prominent divergent lobes. In length it is about 

 two-thirds of the first trunk segment. 



The Ocular tubercle is rather stout, not quite clear of the first pair of lateral pro- 

 cesses. It is tall, rounded at the extremity, where there are four well-developed eyes. 



The Abdomen is not articulated to the trunk, very distinctly pyriform in shape, and 

 not quite so long as the cephalon. 



(ROY. soc. EDIN. TRANS., VOL. XLVI., 173.) 



