546 Dr. W. T. Caiman on an Epizoic Hydroid 



so like tliat of the typical nigricanda both in general colour 

 and dimensions that there can be little doubt that they 

 represent the same species. The following dimensions are 

 those of an adult male nigricauda collected by Dr. Ansorge 

 at Horabom^, JMossamedes, Angola : — 



Dimensions (measured in the flesh) : — 



Head and body 160 mm.; tail 191; hind foot 31; 

 ear 22. 



Skull (broken) : zygomatic breadth 19 ; length of nasals 

 15'2 ; palatilar length 17'6; length of palatal foramina b"7 ; 

 alveolar length of U])per molar series G. 



The much smaller size and paler colour at once distinguish 

 the Molopo race from true nigricauda. 



The following is Mr. Woosnara's note on the habits of 

 this rat : — 



" These mice frequent the Kameel-thorn forests all over 

 the Kalahari, especially where the trees are large, and they 

 seem more numerous in the neighbourhood of water. They 

 breed and spend all the daytime in the trees, only coming 

 down on to the ground at night to feed. Tiiey generally 

 choose an old hollow tree, into which a great quantity of dry 

 grass is packed, sometimes as much as 20 feet from the 

 ground. By setting fire to the nest they are easily smoked 

 out, but not so easily caught, as they are very expert 

 climbers and jump from the ends of a bough into a bush and 

 so to the ground and escape in the grass." 



LXIV. — An Epizoic Hydroid on a Crab from Christmas 

 Island. By W. T. Calman, D.Sc. 



(Published bj' permission of the Trustees of the British Museum.) 



Among the Crustacea obtained by Mr. 11. Kiikpatrick on a 

 recent visit to Christmas Island (hulian Ocean) is a small 

 crab belonging to the family Xanthidje, which attracted 

 notice by liaving a hydroid polyp attached, like a tassel, at 

 the " knee " of each of its legs. 



AVhile it is very common to find h3'droids attached to 

 spider-crabs of the group Oxyrhyucha, it is much more rare 

 in the case of crabs belonging to other divisions of the 

 Brachyura. Further, in the Uxyrhyncha the association is 

 more or less accidental, the hydroids being no more closelv 

 or constantly connected with the crab than any of the other 



