354 



NATURE 



\August 1 8, 1 88 1 



which he re-named Lake Leopold. Mr. Thomson did 

 not succeed in reaching the actual shores of the 

 lake. 



" The point where we halted was upwards of 7000 feet 

 above the sea, and from the fact that the River Mkafii, 

 which flows into the lake, is only about 3000 feet, at 

 a distance of sixty miles north, I infer that Lake Hik«a 

 is not far from being on a level with Tanganyika. So 

 steeply do the moimtains descend, that from the place 

 where we halted we could almost throw stones into the 

 lake ; only we lost sight of them before they reached the 

 ground. The general altitude of the surrounding ranges 

 must be quite 8000 to 9000 feet, and they extend in a quite 

 unbroken line all round. At the north end I calculate 

 the breadth of the lake at about twelve miles. Further 

 south the breadth varies from fifteen to twenty miles. 

 Longitudinally it lies north-north-east and south-south- 

 west. Its length, from native report and from my proxi- 

 mity to it in passing between Nyassa and Tanganyika, I 

 conclude to be certainly not less than sixty miles, probably 

 seventy. Between the mountains and the shores there 

 lies a narrow dark green strip of smooth land, apparently 

 representing a once higher level. On this there are many 

 villages, and the ground is highly cultivated. At the 

 north end, as 1 have already stated, this strip broadens 

 out into a marshy expanse, formed doubtless by the 

 detritus of the River Mkafu." 



Although the waters are almost certainly fresh, yet the 

 lake seems to have no outlet. Without accident or 

 obstacle to speak of, the Expedition, proceeding by 

 Unyamyembe, reached Zanzibar, not much more than 

 a year after it set out from Behobeho. Mr. Thomson, 

 with good reason, congratulates himself that he never 

 needed to fire a shot either in offence or defence, and 

 that, besides the loss of Mr. Johnston, he left only one 

 man behind him. 



The Expedition is in many ways one of the most suc- 

 cessful that ever entered Africa. Not only was it con- 

 ducted with unusual efficiency, not only were the chiefs 

 and people, with few exceptions, friendly throughout, but 

 for the first time we have obtained trustworthy observa- 

 tions on the geology of the great lake region of Central 

 Africa. The main conclusions reached by Mr. Thomson 

 have already been described by himself in these pages. 

 But he did not confine himself to geology. He gives us a 

 fair idea of the general character of the country traversed, 

 its mineral, vegetable, and animal productions, the cha- 

 racteristics and habits of the people, the nature of the 

 work being done by missionaries, and the capacities of 

 the country for industrial development. On the last point 

 his views are far from being sanguine. He maintains 

 that the resources of Central Africa have been greatly 

 exaggerated, especially as to its minerals. We are in- 

 clined to think that on this point he has taken much 

 too gloomy a view, and that, whatever may be the case 

 with the region actually visited by him, there certainly 

 appears to exist, in the districts traversed by Cameron, 

 Livingstone, and more recently by Major Serpa Pinto, 

 stores of iron and copper that may at a future time be 

 turned to great industrial account. Young as Mr. Thom- 

 son is, we commend his remarks on missionary work to 

 those whom it most intimately concerns ; and we trust 

 that his severe, but evidently just, criticisms on the con- 

 duct of the various Belgian expeditions in Africa will 

 receive the attention they deserve from the management 



of the International African Association. In the Appen- 

 dices are given notes on the natural history collections, 

 and Mr. Thomson discusses the geology in detail, sug- 

 gests that at one period the whole of the lake region of 

 Central Africa must have been covered by the sea, the 

 basin of Tanganyika, however, having been formed sub- 

 sequently by a great fault or narrow depression of great 

 though unknown depth. 



Prefixed to the volumes are portraits of Mr. Johnston 

 and Mr. Thomson, and appended a route map and an 

 interesting geological chart. 



OUR BOOK SHELF 



Marine Alga of New England and the Adjacent Coast. 

 By Dr. W. J. Farlow. (Washington, 1881.) 



This valuable essay on the " Marine Algas of New 

 England" is a reprint from the United States Fish 

 Commission Report for 1S79. It includes a list of all the 

 species of sea-weeds, with the exception of the diatoms, 

 which are known to occur on the coast of the United States, 

 from New Jersey to Eastport, Me. Prof Farlow gives in 

 a compact and more or less popular form a description of 

 the various orders and species, and he adds a short 

 account of the general structure and classification of sea- 

 weeds, so that all persons frequenting the coast of New 

 England are thus furnished with a handy and compact 

 manual of the subject. The fifteen excellent plates drawn 

 by J. H. Blake and W. G. Farlow deserve a special 

 notice, as they give details of structure which will enable 

 the te.xt to be understood by an intelligent student. 



Since the appearance (1852-57) of Harvey's classic 

 work on the North American Alga:, but few species 

 have been added to the Flora. This is not perhaps so 

 surprising as regards the Florideas or Fucoids, to which 

 Harvey paid so much attention ; but as regards the uni- 

 cellular or simple filamentous forms it is a cause of sur- 

 prise, for Harvey never paid minute attention to these ; 

 and it may in part be accounted for that collections do 

 not seem to have been made along the coast in spring. 

 Prof. Farlow gives a most interesting sketch of the geo- 

 graphical distribution of the species met with. Cape Cod 

 is, as was known to Harvey, the dividing line between a 

 marked northern and southern flora, and subsequent 

 observation shows that on the one hand the flora north of 

 the Cape is more decidedly arctic th.n he supposed, 

 and that on the other hand that south of the Cape 

 is more decidedly that of warm seas. A good share 

 of the commoner species are also natives of Great 

 Britain, another large share are Scandinavian ; but while 

 this is the case the marine flora is also marked by the com- 

 plete absence of many common British species. No mem- 

 bers of the order Dictyotacete are to be found ; no species 

 of Cutleria or Tilopteris are to be met with. The species 

 of Nitophyllum may be said to be wanting. That com- 

 monest of our red sea-weeds, Plocaniiuni coccincuni, is 

 known as native by only one doubtful case. Fucus 

 canaliculatus, Hiinantlialia loyea are quite wanting. 

 The nearly ubiquitous Codiiim tonieiitosuni has not yet 

 been found. Fiicns serratiis is very rare, having only 

 one locality recorded for it in the Linited States and one 

 in Nova Scotia. Gelidiiim corneiun, abundant in almost 

 all parts of the world, is only occasionally found in New 

 England, and then only in the starved form known as 

 G. crinale. 



Prefixed to the orders and genera will be found carefully- 

 written diagnoses, and an artificial key to the genera is 

 also added. The notes in smaller type which are given 

 under the species often contain most valuable critical 

 information, which will command the attention of all 

 phycologists. To the critical students of our native 



