134 NATURAL SCIENCE. August. 



conducted by the walls of the mantle." We will not pause to show 

 that this consists but ill with the statement on p. 151 that "in the 

 Scaphopoda respiration is by means of branchiae " ; for that is equally 

 incorrect. The heart of Dentalium was first observed by W. Clark, 

 who described its action in 1849 {Ann. Mag. Nai. Hist. (2), iv., p. 321). 

 Lacaze-Duthiers, though he saw the structure, did not regard it as a 

 heart ; but the recent observations of L. H. Plate [Zool. Jahrb. Anat., 

 v., pp. 325-328, 1892) have proved the point definitely. The heart is 

 a small simple sac situated in a pericardium ventral to the median 

 prolongation of the two nephridia and the stomach. Respiratory 

 chambers are also present in the mantle, on the opposite side to the 

 anus ; these, however, are not homologous with the ctenidia of other 

 Mollusca, which some have sought to homologise with the head- 

 tentacles. Had space permitted, a few genial remarks might have 

 been made on Mr. Cooke's treatment of shell-formation and shell- 

 growth, where he has attempted with more valour than success to 

 assimilate modern ideas. He and our readers may be referred to the 

 excellent thesis by Moynier de Villepoix, " Recherches sur la 

 formation et I'accroissement de la coquille des Mollusques," Paris, 



1893- 



If it has seemed the critic's duty to point out a few blemishes in 



the book, it is also his duty to praise it for its readable style, in which 



lapses such as " this must have degenerated their appetites " (p. 33), 



are not very common. He must also praise Mr. Edwin Wilson for 



the beautiful illustrations, and congratulate the publishers on their 



enterprise in attempting a popular Natural History in which the 



Invertebrata are allowed their fair share of space. The chapters on 



the Brachiopoda, with which the volume closes, will receive a separate 



notice. F.A.B. 



North Africa. 



Stanford's Compendium of Geography and Travel (new series) — Africa. 

 Vol. i., North Africa. By A. H. Keane, F.R.G.S. London: Edward Stanford, 

 1895. 8vo. Pp. xvi., 639, with nine maps and seventy-seven illustrations. 

 Price 15s. 



In Stanford's Compendium of Geography no volume was more useful 

 than that on Africa, by Keith Johnston, for the subject matter was 

 more limited, and the information buried in sporting journals and 

 travellers' diaries. After passing through four editions, however, that 

 work was hopelessly out of date, and the editor of the series has 

 wisely now abandoned the attempt to remodel it, and trusted to 

 Professor Keane the task of rewritmg the whole book. The materials 

 have grown so rapidly that Africa now requires two volumes, and the 

 present one deals only with that part of the Continent north of a line 

 from the Gulf of Guinea to the mouth of the Juba. Professor Keane 

 commences the book by an admirable introductory chapter, opening 

 with the paradox that Africa is a land of contrasts, instead of a land 

 of uniform monotony. He contrasts the dense forests of the Congo, 

 the broad grassy steppes of the interior plateau, and the sandy wastes 

 of the Sahara and the East African Nyika. He compares the low 

 lying malarial deltas and coast plains with the bracing uplands of 

 Mashonaland ; the magnificent waterways of the Congo, Nile, and 

 Zambesi, with the areas of inland drainage, and the dry valleys of the 

 Soudan ; the arid climate of the Sahara, and its great diurnal range 

 of temperature with the perpetual snows and fogs of Kilima Njaro 

 and Ruwenzori, and the uniform temperature of such humid localities 



