39« 



NATURE 



[November 24, 192 1 



the Zanzibar coast. His correspondence ceases 

 with the middle of 1890. It contains interesting 

 allusions to Dr. Sclater and other English orni- 

 thologists, to Dr. Junker, and to mertibers of 

 Stanley's expedition, and a rather pathetic touch 

 in his own assumption of the role of the Wander- 

 ing Jew. 



Though this volume deals mainly with the birds 

 of equatorial East Africa, it has some very inter- 

 esting notes on the mammals. Emin had become 

 aware of the presence in East Africa proper of 

 a striped form of hyena, unknown to him in any 

 survey of the Upper Nile regions. More than 

 this — he has noted hints as to the existence in 

 the Mangbettu or Mabode country, within the 

 north-eastern limits of the Congo basin, of some 

 type of "zebra." There is no zebra — so far as 

 we are advised — within the limits of the Congo 

 basin, or west of Tanganyika, or even of the main 

 stream of the Nile. No type of equine — zebra or 

 wild ass — has been seen west of the Nile within 

 the Bahr-al-ghazal basin. It is clear that these 

 scraps of information reaching Emin indicated 

 not any zebra, straying beyond the habitat of 

 this striped horse, but the okapi. 



Dr. Junker, about 1886, wrote a note or two 

 about a large antelope which was found in the 

 southern part of the Mangbettu country, and 

 which had a portion of its hide curiously striped. 

 He seems to have been aware that the creature 

 had cloven hoofs, and therefore did not style it a 

 zebra; but he had evidently seen the strips of 

 striped skin on the limbs of the okapi with which 

 the forest negroes decorated their bodies. Stanley 

 in 1889 heard stories of the okapi from the 

 pigmies, and styled it "a large donkey." This 

 volume will be of very great interest to orni- 

 thologists. H. H. Johnston. 



Our Bookshelf. 



The Clayworker's Handbook. By A. B. Searle. 

 Third edition, revised, enlarged, and largely 

 rewritten. Pp. viii + 381. (London: C. 

 Griffin and Co., Ltd., 1921.) 215. 



This handbook is a useful compilation from cata- 

 logues, journals, year-books, etc. There is little 

 or no attempt to show the original sources, and 

 special work like that due to Mr. Bernard Moore 

 is incorporated without reference to the dis- 

 coverer. For the protection of the author him- 

 self, it would have been better had he given the 

 authorities for some of the extraordinary state- 

 ments made. There are so many of these that 

 the book wants using with some caution. For 

 example, it is said that " ball clay should not 

 leave any residue on a sieve of 120 holes per linear 

 inch." Anyone familiar with ball clays knows 



NO. 2717, VOL. 108] 



that this is wrong, and anyone not familiar 

 with those clays would appear foolish if 

 he rejected a delivery on this authority. 

 We are also told that "enamels are always 

 opaque," and there are several other mis- 

 leading statements of like calibre. The table of 

 common chemicals and their scientific names and 

 formulae would be much improved if it was 

 revised by a chemist, for some of the scientific 

 names are hopeless, likewise the formulae. For 

 example, " sodalite " (common term) is "a 

 felspar" (scientific term); gypsum and plaster 

 are both given the formula CaS04-2H20, and the 

 same mistake is made higher up the page, while 

 flint is given as amorphous silica. Some of the 

 names of defects are translated literally from the 

 German, instead of into the terms generally 

 employed in this country. 



The book serves a useful purpose; the data 

 are handy for reference, and they are skilfully 

 arranged. It is with the object of getting it 

 seriously overhauled that the unpleasant task of 

 emphasising some of the mistakes has been 

 undertaken. 



Liverpool Marine Biology Committee: L.M.B.C. 

 Memoirs on Typical British Marine Plants and 

 Animals. Edited by Prof. W. A. Herdman and 

 Prof. J. Johnstone. No. 24, Aplysia. By 

 Nellie B. Eales. Pp. viii + 84 + 7 plates. (Liver- 

 pool : University Press, 192 1.) 4s. 6d. 



The present is the twenty-fourth Memoir, pub- 

 lished after a considerable interval, of the well- 

 known L.M.B.C. series. The animal with which 

 it deals is a member of the Opisthobranchiata, one 

 of the two orders of Euthyneura, to the other of 

 which, the Pulmonata, belong the ordinary land 

 snails. Though one of these latter animals is 

 very usually studied in the laboratory as an ex- 

 ample of Gastropoda, Aplysia presents several 

 advantages as a type for dissection. It is the 

 largest British Gastropod. It exemplifies a number 

 of morphological tendencies, and exhibits inter- 

 mediate characters between the primitive and 

 more specialised forms. Its internal organs 

 " afford numerous links in the chain of evidence 

 that detorsion has taken place." The palliovis- 

 ceral nerve cords are long (as in Streptoneura), 

 but uncrossed (as in Euthyneura in general) ; the 

 nervous system is less markedly concentrated than 

 in many other Euthyneura, and the animal ex- 

 emplifies the tendency to disappearance of the 

 shell and mantle-cavity. 



The present account will be useful as a labora- 

 tory guide; directions for dissection are given, 

 intercalated in brackets at the necessary places in 

 the anatomical description, and the plates are 

 adequate in number and clearly drawn. An inter- 

 esting section on the history of our knowledge of 

 the animal is prefixed. 



The first line of the book contains a curious 

 inversion ("The Mollusc of which the present 

 Memoir is the subject ") ; and the word " factors " 

 on p. 41 (for "tributaries") reads awkwardly. 



