PYCNOGONIDA. 35 



CH.ETONYMPHON AUSTRALE, var. AUSTRINORUM. 

 (Plate IV., fig. 4 ; Plate X., fig. 15.) 



Although no specimens of ChsetonympJion australe were taken by the ' Discovery,' 

 yet a large number of individuals of a closely allied species were taken in Winter 

 Quarters, chiefly at the beginning of our stay there, before the ship was frozen in, and 

 while dredging was still possible within the 20-fathom line. 



At first sight these specimens seem to be a distinct species ; they are half as large 

 again or more, and their setose covering is finer. The intervals between the lateral 

 processes are much greater, and this is the only character of importance that separates 

 them. Another feature of doubtful value lies in the fact that the tarsus and propodus 

 together are distinctly shorter than the femur. In C. australe these two joints are as 

 long as the femur, or very little shorter, but the slight variation that occurs prevents 

 the acceptance of this fact as a reliable specific character. 



The setose covering has already been alluded to as finer ; it is so, but subject to 

 considerable variation both as to quality and quantity. In average specimens there are 

 large spinous setae on the tibiae, especially on the second. These are, for the most 

 part, arranged in a line but not very distinctly. Two dorsal rows, and a lateral row 

 each side can be distinguished, these are most prominent on the second tibia. There 

 may also be a mid-ventral row of very small spinous setae, rather closely set. Both 

 in C. australe and the specimens from Winter Quarters the ventral setae of the 

 femora and the two tibiae are much less conspicuous than elsewhere. In many indi- 

 viduals there is a conspicuous mid- ventral row of setse on the tarsus ; these are closely 

 set and about as long as the diameter of the joint. 



Two specimens were taken in lOOfin. off Coulman Island ; of these one is com- 

 paratively small. The Ocular tubercle is rather more conspicuously flattened and very 

 slio-htly constricted below the eyes. The setae are as in the Winter Quarters 

 specimens, but without the spinous rows which, as before noted, are not always obvious. 

 Two other specimens were taken off the Barrier in 300fm. Lat. 78 25' 40" S., 

 long. 185 39' G" E. These are both males, one with young. In these the Ocular 

 tubercle is flattened, as in the Coulman Island specimens, and the terminal claw of tin- 

 leg is rather longer and more slender. The setose covering of the legs is very much 

 finer, but its arrangement is exactly the same. 



It is quite impossible to find a distinct character by which these specimens can be 

 separated from C. austral', therefore I feel compelled to regard them as a variety only, 

 and a more southern form of that species Some comparative measurements are given 

 below. 



C. australe. C. austrak, var. austiinornm. 



W. Q. Coulman. Barrier. 



Length of entire body . . . . 8111111. 11 7 12 \-> 



Length of body 6mm. 8 5'5 'J'5 9'5 



Length of trunk, to insertion of abdomen 4'5mm. 047 7 



