52 



NA TURE 



[May 17, 1906 



Each species is fully described, and a careful account 

 of its distribution in Tunis, with some observations on 

 its range in the neighbouring Mediterranean countries, 

 is followed by an interesting and graphic account of 

 its nesting habits, song, and life-history generally. 



The four natural divisions into which the Regency 

 may be divided appear to have each certain species 

 peculiar to it, or more abundant in it than in the other 

 regions. Besides this, in the case of some resident 

 species, such as the crested- larks, for instance, 

 different forms of the same species are to be found in 

 the different regions, the variation of these forms 

 being in some cases considerable, and not always 

 limited to the coloration of the plumage alone, but 

 occasionally extending to the structural parts of the 

 birds. The crested larks, says the author, afford a 

 striking example of the extent to which local varia- 

 tion may bo carried by natural causes, and no country 

 probably affords a better opportunity of observing and 

 studying this subject than Tunisia. The author is 

 naturally in favour of recognising subspecies, and the 

 use of trinomials for them; and his remarks hereon 

 and upon what constitutes a species and a subspecies 

 may be read with great advantage. 



Many noteworthy and peculiar birds may be studied 

 in Tunisia, but probably the families of larks and 

 chats are better represented than any other; of the 

 former twenty-one and of the latter eleven species 

 and subspecies are treated, and the fifteen beautifully 

 e.xecuted coloured plates which adorn these sumptuous 

 volumes are largely devoted to illustrating these two 

 families. Tunis is indeed especially rich in larks ; and 

 vears of study, a long series of specimens collected 

 by himself, and an examination of the various types 

 in museums and the literature of the subject, added 

 moreover to his having had the advantage of observ- 

 ing the birds in life, have enabled the author to clear 

 up many puzzling points respecting the specific and 

 subspecific value of the numerous forms of larks. We 

 have here a very clear and lucid e.xposition of the 

 larks of the western Mediterranean basin ; and 

 especially of the crested larks (the most puzzling of 

 them all), of which the author considers that there 

 are two distinct groups, viz., one including the 

 common crested lark of Europe, the other the small- 

 billed crested lark of Southern .Spain, each with its 

 allies. 



The necessity for protective colouring is un- 

 doubtedly great in a country like Southern Tunisia, 

 where the scanty vegetation affords but little shelter 

 to its feathered denizens. Hence it is that the plumage 

 of most of the species resident in the desert and semi- 

 desert region harmonises with the sandy color- 

 ation of the soil. This is especially remarkable in 

 the larks. But the author points out that although at 

 first sight it may appear curious that the chats, 

 except in a few instances, are more or less con- 

 spicuously coloured, it will, however, be found that 

 the conspicuously attired chats frequent, as a rule, 

 rocky and broken ground full of dark clefts and fissures, 

 where the rocks are sometimes black and in other 

 cases of a glittering white, and in such situations a 

 strongly marked plumage is really far less con- 

 NO. 1907, VOL. 74] 



spicuous than a uniform light coloured one would be. 

 The ravens also remain as black as ever, but they, 

 too, frequent cliffs and rocks for the most part, and 

 their case seems analogous to that of the rock-haunt- 

 ing chats. Two good maps enable the reader un- 

 acquainted with the country to follow the author's 

 remarks on its topography. O. V. Apli.n. 



AUCEBM AND THEIR ALLIES. 



British Fresh-water Rhizopoda. Vol. i. By James 

 Cash, assisted by John Hopkinson. Pp. X+148 + 

 xvi plates. (Ray Society, 1905.) Price 12s. 6d. 

 net. 



THE important discoveries that have recently been 

 made on the morphology of Protozoa have 

 revived the interest in British fresh-water amcebae 

 and their allies, and a monograph on the subject has 

 been regarded for some time as a special need of the 

 zoologist. 



Mr. James Cash has been known for some years 

 as an ardent microscopist with a special knowledge 

 of the forms and habits of the species of fresh-water 

 rhizopoda in the north of England, and he has given 

 us in this volume the benefit of his experience in 

 this line of work, illustrated by many beautiful 

 original drawings of the living organisms. As a 

 work of reference for the names of species, and in 

 so far as it suggests to the young amateur naturalist 

 exercises for his amusement and instruction, it will 

 be useful ; but as references to important details of 

 structure and reproduction are in general meagre, 

 often misleading, and in many instances omitted 

 altogether, it will not supply the need that is felt. 

 The description of the cell (p. 3) as " physiologically, 

 a minute vesicle, or closed sac, the enveloping mem- 

 brane or cell-wall enclosing the protoplasmic sub- 

 stance in which the functional phenomena reside," 

 appears to us singularly unfortunate in an introduc- 

 tion to the study of the Protozoa. 



The description of the nucleus is very short, but 

 long enough to contain considerable extracts from the 

 w-ork of Calkins, whose views the author adopts, 

 but there is no reference to the chromidial network 

 which the recent papers of Hertwig, Schaudinn, and 

 others have shown plays such an important part in 

 reproductive phenomena of many rhizopoda. It is 

 disappointing to find no reference, either in the intro- 

 duction or in the systematic part, to the evidence of 

 a developmental cycle in the life-history of Amoeba, 

 based on the researches of Scheel and Calkins. 



In the very brief account of the reproduction of 

 Arcella, again, although Hertwig's important paper 

 published in Kupffer's Festschrift is included in the 

 list of references, the statements made are incomplete 

 and misleading. Many other criticisms similar to 

 these could be made, but the critic is disarmed by the 

 confession in the preface that the author has not 

 " investigated very closely the physiological problems 

 associated with the life-history of these organisms." 

 With this confession before them, it seems difficult 

 to account for the action of the council of the Ray 

 Society in undertaking the publication of this mono- 



