Vol. 5, p. 279-284. June 11, 1930. 



Occasional Papers 



OF THE 



Boston Society of Natural History. 



REDESCRIPTION OF ARMADILLONISCUS 



ELLIPTIC US (HARGER) WITH SOME 



ACCOUNT OF ITS HABITS. 



(ON ISOPODA 0NISC0IDA, FIRST PAPER.) 

 BY CHARLES H. BLAKE. 



Three definitely halophile land isopods occur in the Woods 

 Hole region: Scyphacella arenicola, Armadilloniscus ellipticus, 

 and Trichoniscus halophilus. The first two belong to the family 

 Scyphacidae, the third, which will be described elsewhere, to the 

 Trichoniscidae. 



In 1878 Harger described a land isopod from near New Haven, 

 Conn., under the name of Actoniscus ellipticus. Except for a few 

 specimens from Bermuda seen by Miss Richardson, it does not 

 seem to have been taken again until May, 1929, when I secured a 

 few specimens at Woods Hole, Mass. In September I was able 

 to obtain a considerable number and to make some observations 

 on the living animals. 



Occurrence. — The specimens taken in May were on a stone near 

 high watermark under wet, dead eelgrass (Zostera 'marina) and 

 associated with them were Trichoniscus halophilus, Procellio 

 scaber, and Armadillidium vulgare. Those taken in September 

 were in windrows of well-rotted eelgrass just below high water- 

 mark. They are most common on pieces of driftwood embedded 

 in the mass and less common on stones and on the grass itself. 

 They are found only in thoroughly wet situations. At this time 

 their associates were a small, slim diplopod, a linyphiid spider 

 and young P. scaber and A. vulgare. 



Habits. — When a specimen in its normal habitat is disturbed 

 the reaction varies. An occasional specimen will run away. 

 Most specimens on a flat surface appress themselves to it and 

 remain motionless. If turned over on the back, they remain 



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