282 MR. G. P, FARBAN ON COPEPODA 



cattle with a flat poll (as in the modern Galloway and in polled 

 Cadzow cattle) obviously belong to the Urus type, while those 

 with a mesial prominence seem to belong to the frontosus type of 

 ISTilsson. As there were hornless cattle in Egypt as early as the 

 Fourth Dynasty, we are not likely soon to ascertain where or 

 Avhen polled breeds originated. There is no evidence that any 

 of the varieties of polled cattle are descended from hornless wild 

 ancestors; neither is there certain evidence of a pure horned 

 race suddenly producing polled offspring. If, as seems highly 

 probable, the absence of horns is not due to reversion, the polled 

 condition was either acquired by the gradual reduction in the size 

 of the horns or suddenly, ?'. e. by mutation. In polled breeds 

 which now and then produce individuals with " loose horns " the 

 polled condition Avas perhaps acquired slowly, while in polled 

 breeds in which " scurrs " are unknown the polled condition was 

 perhaps due to a mutation. Though the Galloway and the white 

 polled " wild " Cadzow cattle may have descended from Bos 

 primigenius, the white polled Somerford, and the round polled 

 Aberdeen- Angus cattle with the premaxillfe extending well vip 

 between the maxillse and nasals, may be the descendants of an 

 Oriental race allied to a modern Syrian breed apparently in the 

 act of losing the horns. 



13. Plankton from Christmas Island, Indian Ocean. — I. On 

 Copej)oda of the Family Corycmdce. By George P. 

 Fare AN *, 



[Received Octoljev 31, 1910 : Read February 7, 1911.] 

 (Plates X.-XIY. t) 



Through the kindness of Dr. W.T. Caiman I have had theoppor- 

 tunity of examining the Copepoda of a small collection (8 bottles) 

 of Plankton, made by Sir John Murray, K.C.B., F.R.S., and 

 Dr. C. W. Andrews, F.R.S., at Christmas Island in the Indian 

 Ocean, and presented to the British Museum by Sir J. Murray. 



The gatherings were all made at approximately the same time 

 (July- August, 1908) and in the same locality, on the north side 

 of the island in shallow water neai- shore, and for this reason 

 it has not been thought necessaiy to refer to each of them 

 separately. 



The collection, though small in bvilk, is exceedingly rich in 

 species, and the genus Corycceus is especially well represented. 



It has been recognized that there are, in the the genus Cory- 

 cceus, two groups differing from each othei' in several distinct 

 characters, the most notable being the form of the ventral 

 process, situated between the maxillipedes and the fii-st pair of 



* Communicated by Dr. W. T. Calman, F.Z.S. 

 t For explanation of the Plates see ^. 296. 



