244 Dr. W. T. Caiman on Pycnogonida 



Type. Adult female. B.M. no. 20. 7. G. 8. Original 

 number 5884. Collected 11th May, 1917, by L. M. Dinelli. 



Although undoubtedly very closely allied to C. juris of 

 Jujuy, this tuco-tuco differs from it by so many little cha- 

 racters that it seems to deserve a special name. The rather 

 larger but still allied species C. lalro occurs between the two. 



XXXI. — On a Collection of Pycnogonida from the South 

 Orkney Islands. By W. T. Calma'n, D.Sc. 



(Published by permission of the Trustees of the British Museum.) 



The Museum has recently received from Mr. A. G. Bennett, 

 a small collection of Pycnogonida dredged in shallow water 

 at the South Orkney Islands. Among other specimens of 

 interest it includes an example of the remarkable Decolopoda 

 antarcttca, hitherto known only by the single individual 

 described fifteen years ago by Prof. Bonvier. 



Decolopoda antarctica, Bouvier. 



C'olossendeis antarctica, Bouvier, Bull. Mus. Hist. Nat. Paris, xi. 1905, 

 p. 295. 



Decalojwda antarctica, Bonvier, C. R. Acad. Sci. cxlii. 1906, p. 17. 



Decolopoda antarctica, Bouvier, " Pvcnogouides du ' Fran9ai8,' " Exped. 

 Antarct. Frau9. (1903-1905) 1906, p. 21, pi. i., pi. ii. figs. 1-5, text- 

 figs. 1 & 2. 



Locality. — Scotia Bay, South Orkneys ; one female. 



liemarks. — The specimen hardly differs in size from 

 Bouvier's holotype (also a female), and, except as regards 

 the palps, it agrees very closely with his description and 

 figures. Bouvier states that the palps consist of eight 

 segments, while those of 7X australis consist of nine, excluding 

 in both cases the basal prominence. In the present specimen 

 the palp of the left side lias eight segments and the terminal 

 one is rounded at the tip and only a little more slender than 

 the preceding. The right palp, however, has ten segments, 

 and the terminal one is slender, curved, and claw-like. It 

 may be assumed that this right palp is abnormal, possibly as 

 a result of regeneration following injury; but I know of no 

 other case ot abnormality in this group in which the number 

 of segments is greater than the normal. 



The assumption of a claw-like form by the terminal segment 

 may, perhaps, be regarded as a case of homoeosis, since. 



