Notices of Memoirs — Report on Southern Rhodesia. 469 



know differs very much from modern biology in the nature of the 

 specimens with which it has to deal ; but even so, would a vertebrate 

 palaeontologist of any standing found a genus and species on the 

 common leg-bone of a mammal because it was too decayed to recognize 

 exactly to which mammal it belonged ? 



Dr. Knowlton, with the zeal for the technical application of their 

 rules of nomenclature which characterizes a certain school of biologists 

 in America, who take every opportunity these technicalities give them 

 of renaming other people's species, has made himself responsible for 

 Benstedtia Benstedi. A genus and species must be capable of diagnosis, 

 and it now devolves on Dr. Knowlton to provide that diagnosis. 



NOTICES OF HVCIEIMIOIIRS- 



I. — Geological Survey of Southern Rhodesia. 

 TIIHE following particulars are extracted from the Report of the 

 X Director, Mr. H. B. Maufe, for September to December, 1910 

 (Salisbury, Rhodesia, 1911): — 



Headquarters have been established in Bulawayo for the purpose of 

 working in co-operation with the geological and mineralogical section 

 of the Rhodesia Museum. The provision of a suitable topographical 

 map is a question of prime importance. The farm plans compiled by 

 the Surveyor- General on the scale of 400 Cape roods to the inch form 

 the most suitable available basis for the geological field mapping. 

 They are often far from satisfactory as regards topographical details, 

 and the geologist's time will frequently be taken up in inserting the 

 more important surface features. 



November and December were spent in actual field mapping in the 

 Enterprise Goldfield, situated to the east of Salisbury. An area of 

 50 square miles was finished, and a further area traversed, but not 

 completely mapped. 



The Enterprise Goldfield lies in a district of metamorphic rocks, 

 extending almost thirty miles slightly north of east of Salisbury, and 

 measuring from north to south eight miles or more. On the north, 

 east, and south it is bounded by granite, which is later than the 

 metamorphic rocks and causes contact alteration in them. The 

 metamorphic rocks are divisible into three groups, as follows : — 



(1) A group consisting largely of epidiorite. 



(2) An ironstone group, which also includes some limestones. 



(3) A group of quartzites and conglomerates. 



Each of these groups includes many varieties of rock, some of which 

 occur in two or even three groups, but the groups as a whole are 

 fairly well defined, and seem to correspond with the subdivisions 

 described by Mr. F. P. Mennell in other parts of the country. The 

 greater part of the metamorphic rocks are altered sedimentary rocks — 

 altered conglomerates, sandstones, shales, and limestones. Dp to the 

 present the oii\y igneous rocks met with which belong to the meta- 

 morphic series are the epidiorites foi-ming the larger portion of 

 group (1). Gold occurs in payable quantities in certain bands of 

 schist intercalated in the epidiorites of group (1). Several mines 

 working these bands are being energetically developed. The ironstone 



