48c 



NATURE 



\_March 24, 18S1 



Hooker, Milde, and in the earlier editions of Newman. 

 In North America the order is represented by 139 

 species and 31 genera. The number of species is quite 

 double what we have in the whole of Europe. The 

 northern area outside the United States produces very 

 few species that have not been found within the bounds 

 of the Union. As in Europe there are no Cyatheaceae, 

 Marattiaceffi, nor Gleicheniaceas. Of the other sub-orders 

 the SchizQ^acea;, which we do not possess, are represented 

 in the United States by three genera and four species. 

 Ceratopteris, of which Prof. Eaton makes a special 

 ;ub-order, is also American, but not European. The 

 other four sub-orders — Polypodiacea;, Hymenophyllacea;, 

 Osmundaceffi, and Ophioglossacea: — are represented, both 

 in America and Europe. One peculiarity of ferns is that 

 the genera show exceedingly little tendency to geogra- 

 phical localisation. The nearest approach to this that we 

 have in North America is the predominance of Pellasa, 

 Cheilanthes, and Nothochlasna, which are allied dwarf 

 types with a greater power of resisting drought than any 

 other set of ferns, and which are represented in this area 

 by a large proportionate number of endemic species. 

 These three genera take up thirty-nine species in North 

 America against four for Europe. Out of the 139 species 

 about forty are endemic, and about forty are European 

 the latter including several of our high mountain types 

 such as Cystopteris inontana, Aspidium Lonchitis, Poly- 

 podium alpestre, Woodsia ilveiisis, glabella, and hyperborea. 

 The southern boundary of the States corresponds broadly 

 with the limit in a northern direction of the great tropical 

 flora of Equatorial America, the richest tropical flora in 

 the world. But out of the 139 ferns at least twenty are 

 characteristically widely-spread tropical species which do 

 not extend beyond Florida, which have several of them 

 only been discovered there within the last few years. 

 Such are Ophioglossiim palmatum, Aero:tichuiii aurcum, 

 Polypodiwn aureum, P. Phyllitidis, P. Plumula, and P. 

 pectinatitm, Vitlaria lineata, and Nephrohpis exaliata. 

 Amongst the remaining species there are some curious 

 cases of a role of distribution it is difficult to explain or 

 understand. Adiantum pedtitiim and Osmiinda cinna- 

 monea are examples in ferns of a considerable group of 

 .American plants which reach Asia by way of Japan and 

 run down through China to the Eastern and Central 

 Himalayas ; Pteris serrulata, found lately in America in 

 Alabama, and South Carolina, reappears only in China ; 

 Pclla-a aiidromed<rfolia, which from California passes 

 down the Andes to Chili, reappears in Cape Colony. 

 Nothochlccna tenera is supposed to be divided between 

 Southern Utah and the Andes of Bolivia and Chili, but 

 here I think that the States plant will most likely ha«e 

 to rank as a distinct species. Aspidium mohrioides, 

 long supposed to be endemic in extra-tropical South 

 America, has been discovered lately by Mr. Moseley in 

 Marion Island, and by Mr. Lemmon in one place at an 

 elevation of Sooo feet above sea-level amongst the moun- 

 tains of California. 



As regards the limitation of genera and species Prof. 

 Eaton differs but little from Sir William Hooker, as the 

 English author's views are expounded in his great 

 monograph of the ferns of the whole world, his "Species 

 Filicum." Prof. Eaton treats Hymenophyllaceas and 

 Ceratopterideas as distinct sub-orders ; the former at any 



rate a decided improvement upon Sir W. Hooker's clas- 

 sification, and he maintains Ophioglossaceas as a distinct 

 order. In genera the principal deviations are that he 

 keeps up Phegopteris as distinct from Polypodium, and 

 merges Nephrodium in Aspidium. 



A very curious North American fern is Asphnium 

 ebenoides of Scott. It is very rare, and always grows in 

 company with the walking leaf {Camptosorus rhizo- 

 phyllus) and Asplenium ebenetim, two common American 

 species. These are very dissimilar plants, but A. 

 ebenoides is quite intermediate between them. Prof. 

 Eaton seems not disinclined to the idea that it may be 

 produced by natural hybridisation, as was suggested by 

 the Rev. M. J. Berkeley in the Journal of the Royal 

 Horticultural Society for 1866, p. 87. 



An observation of Prof. Eaton's under Nothochlcena 

 Fenaleri is interesting as bearing upon Milde's classi- 

 fication of ferns into a catadromous .and anadromous 

 series, according as to whether their lowest secondary 

 branches originate on the posterior or anterior side of 

 the pinnae. Prof. Eaton notes that in this species there 

 is always a decided inequality in their origin ; but that 

 it is sometimes on the anadromous, and at others on the 

 catadromous plan. J. G. Baker 



KOLLIKER ON ANIMAL DEVELOPMENT 

 Grundriss der Entwickebtngsgeschichte des Menschen u. 

 der hoheren Thief e. Von Albert Kolliker, Professor der 

 Anatomic an der Universitat Wiirzburg. (Leipzig : W. 

 Engelmann, 1880.) 



THIS book is essentially a reproduction of Prof. 

 Kolliker's large treatise on Embryology, with a great 

 part of the detail and controversial matter omitted, and is 

 intended for the use of medical students. The larger 

 work has more the character of a monograph on the 

 development of birds and mammals than of a text-book ; 

 and as such, though of very great value to those engaged 

 in teaching and research, is necessarily too bulky for the 

 use of ordinary students. We think, therefore, that Prof. 

 Kolliker has done very wisely in publishing the work 

 before us ; and we need hardly say that, his larger treatise 

 having been already universally recognised as one of the 

 most important contributions to embryology during recent 

 years, the present work may safely be regarded as an 

 accurate statement of the facts of avian and mammalian 

 embryology. We may add that no trouble has been 

 spared in the illustrations, which fully come up to the 

 high standard characteristic of German works of this 

 class. 



While, however, we can say this much in praise of 

 Prof. Kolhker's treatise, we cannot help recognising that 

 it has some rather serious defects. Prof. Kolliker is an 

 extremely objective wTiter. He describes with great 

 clearness the objects as they present themselves to the 

 observer, but he scarcely ever attempts to connect them 

 together or to point out the general principles which 

 underlie the mass of detail with which he has to deal. 

 In his larger work this pecuHarity is of comparatively 

 small importance, in that those who are likely to use it 

 are able to supply the general principles for themselves ; 

 and the work has already become a great mine of facts 

 to which every anatomist who is engaged in studying the 

 morphology of vertebrates will necessarily turn. 



