192 



LETTERS TO DR. HOWARD [CHAP. xvm. 



and strained my eyes so badly that I caused delay without 

 much good. 



Now I am trying to work up Piophila casei (Cheese and 

 Bacon fly, fig. 12) as a cheese pest. How curious it is that 

 it should not trouble cured meats with us, as with you nor 

 cheese with you as with us. 



The Shell-slug, Tesiacella haliotidea (fig. 44), seems to me to 

 deserve a little notice, as (by its carnivorous habit) ridding 

 us of various under- and above-ground troubles (slugs espe- 

 cially), and I have been gathering a few notes about the 

 creature for some years. Another (I believe) unusual pre- 



i, Worm extended ; 2, contracted ; 3, 4, and 5, different forms taken 

 by the head all life size (after figures by Prof. F. Jeffrey Bell) ; 6, bifid 

 form of head, rather larger than life. 



FIG. 45. FLATWORM, LAND PLANARIAX, BIPAL1UM KEWENSE. 



sence lately sent me was a specimen of the Ground 

 Planarian, Bipalium kewense, found eating plants ".like a 

 slug." I did not know the worm (so to call it) at all, 

 but the name was given at S. Kensington. When it 

 arrived it looked only like a very narrow slimy strip about 

 three inches long but I thought from its reported habitat 

 possibly some slightly warm water would revive it, and 

 immediately it roused up and swelled to a narrow cylindri- 



