LINNEAN SOCIETY OF LONDON. XCl 



Madeira, we find a multitude of forms described as species, but 

 differing from each other, or from kuown species living in other 

 localities, by such minute characters that, but for their permanence 

 and geographical localization, they would be regarded as mere varie- 

 ties. Por these forms Mr. WoUaston seems inclined to adopt a 

 sort of semi-Darwinism; that is to say, he admits that they may 

 have been produced by modification consequent on the breaking-up 

 of the district into islands ; but at the same time implies that, could 

 this be demonstrated, we should have to suppress the species." 



" The second volume of Dr. Bowcrbank's ' Monograph of British 

 Spongiadte ' appeared in 186G. This work has called forth a host 

 of comments, in which the views of the author upon physio- 

 logical and classificational questions have been rather roughly 

 handled. We may call particular attention to a valuable paper by 

 Prof. James-Clark, read to the Boston Society of Natural History, 

 and reprinted in the 'Annals of Natural History,' on the relationship 

 of the ciliated sponges to the Plagcllate Infusoria, which bids fair 

 to throw some light upon the intricate affinities of the Protozoa. 

 Professor Oscar Schmidt, in a second supplement to his ' Sponges of 

 the Adriatic,' has also entered into a discussion of Dr. Eowerbank's 

 genera." 



M.r. Murray's elaborate work on the Geographical Distribution of 

 .. Mammals, the greater part of it devoted to the discussion of the dis- 

 tribution of the subordinate groups of the Mammalia,is carried outinto 

 considerable detail, and furnishes an excellent guide to this important 

 subject. The numerous maps with which it is illustrated, upon the 

 plan of those adopted in the Kcw Museum in respect of economical 

 plants, are excellent, as exhibiting at one view, for purposes of compari- 

 son, the general areas over which the -several groups extend. Upon 

 looking over them, without having studied the text, I have been 

 struck with the little correspondence shown in their areas with what 

 is known of the geographical distribution of large and widespread 

 genera of plants. The preliminary inquiries show a high apprecia- 

 tion of, though not, in all respects, a concurrence with, the views of 

 Mr. Darwin. Mr. Murray, like many of us, has found reason to 

 alter, in some respects, his former views as to the stabiHty of species ; 

 he now admits their derivative origin and occasional modification ; 

 what he still contends for appears to be that the changes are sudden 

 and directly consequent upon absolute change of condition, and 

 never gradual and continuous, nor dependent on selection in the 

 struggle for life. He refers to views expressed in some of Sir Charles 



