224 NATURAL SCIENCE. march. 



have fossil representatives being included ; while short diagnoses are 

 given of all genera of any palaeontological importance. The work, 

 therefore, is an almost complete synopsis of the whole range of 

 palaeontology. 



The " Handbuch " is, however, by no means merely a compila- 

 tion. Professor von Zittel has always shown himself far too con- 

 scientious a worker to be willing to be content to leave some of the 

 groups he has had to treat in the state of hopeless chaos in which he 

 found them. In nearly every group the author's acumen in inter- 

 preting the descriptions of others, or his researches on the very 

 extensive collections at Munich, have considerably advanced the 

 classification. Take, for example, the Sponges ; before the author 

 came to them in the preparation of his second " Lieferung,' they 

 were in absolute chaos, the descriptions being based almost entirely 

 on points of such little scientific value, that it was totally im- 

 possible to make any satisfactory comparison of the fossil with 

 the recent faunas. The author accordingly at once commenced a 

 re-investigation of the group and devoted nearly two years to 

 the eighty pages in which the Sponges are described ; by the 

 study of thin sections under the microscope the forms of the spicules, 

 were determined and our knowledge of the fossil sponges placed 

 on a scientific basis. In other groups there was less room for such 

 revolutionary changes ; but there are few, if any, which Professor von 

 Zittel has left where he found them. In the Echinoidea he founded 

 the family Conoclypeidae after a study of the internal structure of the 

 peristome, and thus removed one stumbhng-block from the path of 

 echinologists. The classification of the Bryozoa was extremely 

 advanced considering that it was prepared fourteen years ago, while 

 many very sound advances were made in the complicated synonymy 

 of this group. 



In the Vertebrates, which, we believe we are right in saying, are 

 not his speciality, the Professor has in the main followed the classi- 

 fications of those w'ho have made studies of the various groups. 

 Even here, however, he at times strikes out a line of his own. Thus, 

 as we have had occasion to mention in our previous notices, he 

 divides the Mammals into the Placental and Eplacental groups, of 

 which the latter includes both Monotremes and Marsupials ; while in 

 the Ungulates many modifications have been made (whether wisely 

 or unwisely we do not care to discuss on this occasion) in the limits of 

 family groups. 



Perhaps the most valuable contribution which Professor von 

 Zittel has made to this part of his subject is the masterly essay on 

 the geological distribution and evolution of the Mammalia with 

 which the last volume closes.- In the two preceding numbers of 

 Natural Science certain remarks from the pen of an independent 

 observer have been made in regard to the improbability of the extinct 

 mammals of Patagonia being of lower Eocene age ; and it is 

 interesting to note how Professor von Zittel's observations support the 

 view there taken. Thus, the Professor remarks how difficult it is to 

 believe that mammals with such specialised dentition as those in 

 question could by any possibility be correlated with those of the 

 European lower or middle Eocene, and how much more closely they 

 resemble in their grade of evolution those of the upper Eocene or 

 Oligocene ; more especially as they are accompanied by at least one 



2 Dr. G. J. Hinde translated this essay into English and published it in Geo!. 

 Mag., Sept., Oct., and Nov., 1S93. 



