194 



BAKER ON FERN ALLIES. 



togams. In' some of the genera the species are suggestively few in 

 number. Of the Horsetails, for example, — an order gigantically in 

 evidence in the carboniferous era — there are now only twenty known 

 in the whole world, ten being British ; a dying-out genus this one, 

 clearly, under the conditions of historic times. Per contra, the work 

 before us shows there to be 334 species of Selaginella (many beautiful 

 though small in size), of which only one, Selaginella spmosa^ is British, 

 this being a latter-day order so to say, sub-tropical in its distribution 

 for the great part, the product of some mysterious inscrutable 

 environment to which modern science has not, as yet, found the key. 



The fossil types of the Fern AlUes are of course not included in 

 this work, since they have gradually been fully dealt with by Prof. 

 W. C. Williamson in the Philosophical Trafisactions from 1871 

 onwards, although truly, to quote the Preface, a study of these fossil 

 types is quite needful to a correct understanding of their relations to 

 one another and other plants ; and there is an excellent general 

 summary of what is known about them in a translation by Goebel, of 

 the systematic portion of Sachs' Text-book amplified, recently issued 

 from the Clarendon Press. 



The orders and genera are as follow : — II. Equisetaceae. One 

 genus (Equisetum — 20 species, 10 of them British). III. Lycopodiaceae. 

 Four genera, i. Phylloglossum (i species, Australasian). 2. Lyco- 

 podium (94 species, 6 British). 3. Tmesipteris (i species, Polynesian). 

 4. Psilotum (2 species). IV, Selaginellacese. Two genera, i. Sela- 

 ginella (334 species, the first one only being British). 2. Isoetes 

 (49 species, only two of the aquatic and one of the terrestial forms, 

 and none of the amphibious, being British). V. Rhizocarpeae. Four 

 genera, i. Salvinia (13 species). 2. Azolla (5 species). 3. Mar- 

 silea (40 species, 2 European, none British). 4. Pilularia (6 species, 

 I British). 



Errors, of course, as in all that Mr. Baker does, are conspicuous by 

 their absence ; and but very few omissions of recently brought up 

 names, etc., strike us. Wahlenberg's beautiful variety capillare of 

 Equisetum sylvaticuni does not appear to be considered worthy of 

 notice. Misprints and printer's errors are few, though there is a rather 

 funny one in the (as often happens) larger conspicuous type of the 

 Preface — ' amplication ' in place of ^amplification'; and Kuhlwein's 

 Equisehnii litorale is usually spelled with a single, not a double, t. 

 Under species No. 26 on page 40, the surname ' Spruee ' should be 

 ' Spruce.' These are points indeed ; that they are the only ones the 

 reviewer can find to descant upon is, perhaps, the highest praise that 

 could be given to a work that from cover to index (which is full), 

 alike in matter, type, and get-up, is both sightly and good. — F. A. L, 



Naturalist, 



