5i6 



NA TURE 



[October 6, 1923 



exceptional. The geographical and geological features 

 of the mountains beside the Great Rift Valley resemble 

 those of normally faulted block-mountains, and not 

 those of fold mountains due to corrugation of the crust 

 by compression. The topography along the Great 

 Rift Valley agrees with that of areas torn by tension 

 clefts rather than with mountains raised by compres- 

 sion ; for all the faults known are normal ; beside the 

 valley rise many block-mountains and horsts, and it is 

 associated with vast lava fields. In mountains due to 

 compression, on the other hand, the faulting is re- 

 versed ; volcanic action is rare except for isolated 

 volcanic groups some distance from the main chain, or 

 where it is cut across by later faults. The mountains, 

 moreover, occur in long sinuous chains and sheaves of 

 chains which gradually dwindle in height through parallel 

 foothills. That the Rift Valleys are due to tension is 



emphatically asserted by Prof. Krenkel. The fracture 

 zones of East Africa, he says, are zones in which the 

 crust has been torn asunder {Zerreissungszonen der 

 Kruste, p. 169). 



Recent evidence, therefore, from the Zaml>ezi ar.d 

 the Gulf of Suez, Mr. Sikes's fossils from the Kapm 

 Plains, and Prof. Krenkel's valuable monograph, com- 

 bine to confirm the conclusions that the Great Rift 

 Valley was initiated by an upbulging of the crust ; that 

 its fractures were connected with vast volcanic eruptions 

 which began in East Africa in the late Cretaceous, and 

 were contemporary with the Deccan Traps of India ; and 

 that one set of the fractures that made the Rift Valley 

 happened in the Oligocene, These conclusions render 

 it probable that the African Rift Valleys are due to 

 the secondary consequences of the movements that 

 made the basin of the Indian Ocean. 



Obituary. 



Mr. F. J. H. Jenkinson, Hon.^D.Litt. (Oxon.). 



IN Mr. Francis Jenkinson, University Librarian at 

 Cambridge, who died on September 21, has passed 

 away one of the most versatile and distinguished of 

 Cambridge scholars. Of his profound knowledge of 

 classics, of bibliography and antiquarian matters, and 

 of music, this is not the place to write. This notice 

 must be restricted to his activities in natural science, 

 in one branch of which, entomology, he was an expert. 

 Nor is it possible here to give more than the briefest 

 outline of his life. Born in 1853, he entered Marl- 

 borough at the age of twelve, and in 1872 began a 

 distinguished career at Trinity College, remaining for 

 the rest of his days at Cambridge. He became Univer- 

 sity Librarian in 1889, and held this post until his 

 death, a period of more than thirty years. 



Jenkinson was Curator in Zoology in the University 

 Museum for a few months in 1878 (the same year in 

 which he gained his Fellowship at Trinity by his 

 classical attainments). He was the second occupant 

 of this position, the first having been Mr. J. F. Bullar, 

 and during his tenure he worked chiefly at insects. The 

 same curatorship was afterwards filled (in 1890) by 

 the late Dr. David Sharp. But though Jenkinson 's 

 official connexion with the Museum' of Zoology was 

 short, he was its valued helper to the end. 



From boyhood a keen naturalist, and especially a 

 lepidopterist, Jenkinson was much associated in early 

 years with his lifelong friend Mr. Edward Meyrick, as 

 a student of the smallest and most delicate forms. 

 Some time after the coming to Cambridge of Dr. Sharp, 

 with whom he formed a lasting friendship, Jenkinson 

 turned his attention to Diptera. These were henceforth 

 his special study until the last, and it is as a dipterist 

 that he will be remembered in entomological circles. 



It is true of Jenkinson's entomological side, as 

 perhaps of all his interests, that his published works 

 are little in comparison with the greatness of his know- 

 ledge. His writings comprise some twenty-seven short 

 notes and papers, contributed to the Entomologist'' s 

 Monthly Magazine between 1886 and 1922. The first 

 four, up to 1900, deal with Lepidoptera, the remainder 

 almost entirely with Diptera. In his longest paper 

 (1908) he recorded a number of fungus-gnats new to 



NO. 2814, VOL. I 12] 



Britain and described one new to science. The short 

 notes contain records of captures and observations of 

 the habits of various flies. His last entomological 

 writing (1922) was an obituary notice of his old friend 

 A. B. Fam. 



But these publications are only a small part of 

 Jenkinson's dipterological work. None could be more 

 generous than he in aiding other workers. He had a 

 wonderful faculty for distinguishing obscure species 

 in the field, and very great deftness in capturing 

 minute insects, even without a net. He was a very 

 skilful manipulator, and collected a vast amount of 

 material in several parts of Great Britain, but especially 

 in his own garden at Cambridge. The pick of these 

 captures was always at the disposal of the University 

 Museum, to which he gave hundreds of specimens, 

 and he was one of the makers of the Cambridge collec- 

 tion of British Diptera, now one of the largest extant. 

 The national collection at South Kensington has also 

 been enriched by many of his specimens. His mis- 

 cellaneous captures in other orders were frequently 

 interesting : a minute Copeognathe found in a house 

 at Crowborough, and described by Dr. Enderlein in 

 1922 as a new genus and species (Pteroxanium). is the 

 first Psocid {sens, lat.) with scale-covered wings to be 

 discovered in Great Britain, the forms related to it 

 being tropical. 



Jenkinson's faculties for observing were extended to 

 plants, birds, and even, at one time, to mollusca. He 

 applied his classical and bibliographical knowledge also 

 to entomological matters. The former was often called 

 into play in questions relating to scientific names. 

 What he wrote of Earn was true also of himself : " he 

 disliked slovenliness " and " was the most scholarly of 

 naturalists." As Librarian he was always sj-mpathetic 

 to the needs of entomology, and contributed to the 

 result that the University Library- and departmental 

 libraries together now contain a body of entomological 

 literature (especially periodicals) probably unsurpassed 

 in any centre in Great Britain outside London. In 

 person he was tall but of almost fragile build, and he 

 was always hindered by poor health. The kindest- 

 hearted of men, his personality exercised a singular 

 charm over his many friends. H. S. 



