No. 2.] GEOLOGY AND MINERALOGY. 231 



II. 



Trilobita (Fossil, extinct). 



1. Eyes sessile, compound. 



2. No ocelli visible. 



3. (Ai)pendages partly or;il, partly 

 ambulatory, arranged in pairs). 



4. Thoracic segments variable in 



number^ from 6 even to 26, free 

 and movable (animal some- 

 times rolling in a ball). 



5. Al)dominal somites coalesced 



forming broad caudal shield 

 (bearing the branchice be- 

 neath). 



6. Lip-plate, icell developed. 



Should our further researches confirm Mr. Billings's discovery 

 fully, we may propose for the second pair of these groups a 

 common designation (as in the case of the Merostomata) ; mean- 

 time, the above may serve as representing the present state of our 

 knowledae. 



Isopoda (Fossil, and living). 



1. Eyes sessile, compound. 



2. No ocelli visible. 



3. Append;ig\s partly oral partly 



ambulatory, arranged in pairs. 



4. Thoracic segments usually se- 



ven, free and movable (animal 

 sometimes rolling in a ball). 



5. Abdominal somites coalesced, 



forming broad caudal shield, 

 bearing the branchias beneath. 



6. Lip-plate, small. 



BOTANY AND ZOOLOGY. 



Popular Names of Plants. — Botanists generally ignore 

 the use of any other than scientific names for plants, because it 

 leads to a great deal of confusion in their nomenclature, the 

 same name being frequently applied to two or more plants of 

 entirely different species, and sometimes of widely separated 

 genera ; and in other cases the same plant will receive a dozen or 

 more names, varying in difi'erent countries, and even in various 

 sections of the same country, among people speaking the .same 

 language. For precise nomenclature, therefore, the names given 

 by acknowledged authorities in the botanical world have to be 

 accepted by amateurs and professional men. Nevertheless, the 

 popular names of plants are not merely empirical, but are 

 founded, as the scientific names are founded, upon some peculiar 

 feature or use 'of the plant. 



Of late years these popular names have become the object of 

 very interesting research, as throwing much light upon ethnolo- 

 gical history, the antiquity of various nations, and the migra- 

 tions of the larger tribes of men. We can not, of course, go 

 into a lengthy account of these matters, or give the derivation of 

 all the popular names in use — it would require a large volume to 

 do this; but we will give a few examples of the results of the 



