34 NATURALISTS' ASSISTANT. 



If a few of the rings be punctured so as to admit the spirit 

 to the interior of the body this may be prevented. The 

 spirit should also be frequently changed during the first few 

 days. 



Along with the myriapods will generally be found the ter- 

 restrial Crustacea {Oniscida), known under the common 

 names of " Sow-bugs " and " Pill-bugs." These should also 

 be carefuly collected and preserved. These forms are 

 greatly desired as they 'have been almost wholly neglected 

 by American naturalists and but little is known of our native 

 species. Many of them, however, seem to be identical with 

 those of Europe, and no one should attempt to describe them 

 without access to the works of Brandt, Lereboullet, Kinahan, 

 etc. 



MARINE COLLECTING. 



Every portion of the sea teems with life, which varies, not 

 only according to geographical position but also with depth, 

 character of bottom, temperature of water, etc., etc. In 

 different circumstances different methods are employed for 

 collecting. 



Certain forms, principally Amphipod Crustacea and shells, 

 may be found on the shore much above high-water mark. 

 Twice during the day the receding tide leaves a portion of 

 the shore uncovered, and this portion "between tide marks" 

 has its peculiar fauna. For collecting here, one should 

 wear rubber boots and be equipped with bottles, forceps, etc. 

 There should be a considerable variety in the bottles em- 

 ployed. A good idea is to have four or six large jars with 



