TERRESTRIAL ISOPODS. 81 



Feeling, therefore, that something more might be done to 

 increase our knowledge upon this subject, I have devoted some 

 considerable time during the past few months in further study- 

 ing the distribution of these forms within this area, and propose 

 to set forth here, briefly, the results I have obtained, with the 

 hope that some other naturalists might be led to pursue the 

 subject further; for I have but little doubt that careful in- 

 vestigation in the right places will reveal many of these 

 interesting forms. 



While engaged in this work many opportunities, which I 

 gladly accepted, were kindly offered to me for investigating 

 hothouses, orchards, cultivated and other private grounds, to 

 which entrance could be obtained only by express permission. 

 I am now able, therefore, not only to note the occurrence of 

 three additional species, but also to record a much more extended 

 distribution for most of the rarer species already known to 

 exist within this area. 



Terrestrial Isopods, or, as they are commonly called, " Wood- 

 lice," are of retiring habits, and are generally to be found beneath 

 stones, decaying timber, vegetable matter, in manure heaps, 

 and in moss-grown places — in fact, generally in situations where 

 they obtain a certain amount of moisture, which seems to be 

 necessary for their existence, their breathing organs being to 

 some extent branchial in character. 



But I have found a number of species of the genera Onisous, 



Porcellio, Cylisticus, and Metoponorthus living in considerable 



numbers in the hothouses which I have been allowed to examine, 



especially in tomato-houses, where the food is both choice and 



abundant, where there is usually a sufficient amount of moisture — 



at least for these species — due to the regular watering of the plants, 



and where the warmer temperature is evidently appreciated by these 



organisms. The species belonging to the family Trichoniscidae, 



however, do not seem to find the conditions of hothouse life at 



all agreeable, and consequently seem to shun these situations. 



In all probability the amount of moisture is quite insufficient 



for these smaller wood-lice, and in almost all the oases where 



I have found them inhabiting greenhouses, the temperature was 



not much higher than that which obtained outside. It might 



be necessary to state here that all the species I have met 



p 



