REVIEWS. 



Von Bau und Lebbn der Trilobiten. I. Das Schwimmen. 



11. Der Aufenthalt auf dem Boden. Der Schutz. Die 



Ernahrung. By Eudolf Richter. Senckenbergiana, i, 



pp. 213-38, with 8 text-figures, December, 1919. ii, pp. 23-43, 



with 13 text-figares, February, 1920. 



TN the new periodical Senckenhergiava, issued by tlie Museum of 



-*- the Senckenberg Naturalists Society in Frankfurt a. M., Rudolf 



Richter has begun a series of interesting papers on the structure 



and life of Trilobites. Dr. Richter has been led to this by his 



studies of Devonian trilobites, and especially of the curious forms 



found at Gees near Gerolstein and developed with much skill by 



himself and others at the Senckenberg Museum. 



Structurally fitted for a life on the sea-bottom, tlie trilobites 

 frequently remained on the sea- floor, where they crawled on the 

 ooze or on plants, or rested, either rolled up or outstretched and 

 perhaps hidden by a thin layer of sediment. On the other hand, 

 most, if not all, trilobites could swim by the aid of their many oar- 

 like limbs. The smooth Phacops-Proetus type, with its strong 

 muscular body, was the most agile. The spiny or horned type, 

 represented by Ci/'phaspis, Acidasjns, and above all the extra- 

 ordinary Lichas armatns from Gees, was adapted for gentle movement 

 and flotation or balancing in still water. Whether creeping or 

 swimming, when disturbed they rolled up suddenly, and if swimming 

 thus sank rapidly to the bottom. In the roUed-up state the spines, 

 when present, are seen to surround the body. 



When swimming the trilobites probably fed on larv^ and other 

 minute organisms. When creeping they probably shovelled up the 

 decaying fragments of plants and animals, being provided in many 

 cases with shovels, ploughshares, or rakes. They did not, however, 

 burrow deeply into the ooze, but kept on or just below the surface. 

 It will be seen that Dr. Richter's views do not entirely agree 

 with those expressed by W^alcott, Dollo, von Staff, and Reck, and 

 others who have speculated on the subject. But they are main- 

 tained bv ingenious arguments based on material both new and old. 

 F. A. B. 



Doelter's Handbuch der Musteralchemie. 

 T\7E have received from the publishers four instalments of this 

 '* work, which have appeared since 1914. From particulars 

 given on the cover it appears that vol. i, both halves of vol. ii, and 

 the first half of vol. iii are now complete. Of vol. iii there are 

 now to hand parts v-vii. Part v includes a detailed description 

 of a large number of arsenic and antimony minerals, mainly by 

 Dr. H. Leitmeier, of Vienna, and Dr. Hengiein, of Karlsruhe ; 

 part vi includes the minerals of bismuth and vanadium, and a long 



