No. 26.] AETHROSTRACA OF CONNECTICUT. 39 



and yet the species normally abounds in fairly dry surroundings 

 where individuals run about in the dry grass for several hours 

 at a time. Specimens of Orchestia agilis I have found surviving 

 after several hours on a dry laboratory floor in the summer. 



The shore-inhabiting forms must necessarily be able to endure 

 considerable changes in the density of the water. Orchestia 

 palnstris will bear an exposure for several hours to fresh or 

 brackish water. Talorchestia, according to Miss Smallwood, will 

 bear exposure to spring water for six and a half hours without 

 fatal results. 



MOLTING. 



The frequency with which the Amphipoda molt is not known 

 with any degree of certainty. Holmes found that in Amphithoe 

 of the usual size two successive molts took place in seven or eight 

 days. The frequency decreases as the adult size is gradually 

 attained. 



In the process of molting the skin splits transversely along 

 the line joining the head and thorax and on either side of the 

 thorax between the upper margins of the coxal plates and the 

 lower margins of the thoracic rings. The head and antennae are 

 pulled backwards and the posterior part of the body is pulled 

 forwards, the old skin remaining intact except along the splits 

 just mentioned. 



The process may be completed in a quarter of an hour or so, 

 or it may be prolonged over several days. Holmes notes one such 

 case in which the animal died before the molt was completed. 

 Immediately after molting, the animal is rather quiet but in a 

 short time, a quarter of an hour, after the old skin has been shed, 

 it assumes its ordinary activity. The antennae may become broken 

 during this process but no other appendages have been observed 

 to be lost at this time. 



NESTS AND NEST-BUILDING. 

 Those species of Amphipoda which possess glandular pereio- 

 pods habitually occupy tubes which serve as hiding places for 

 them and from which it is rather difficult to drive them. Usually 

 these tubes are cemented to some solid object, but Cerapus 

 tubularis carries its tube about with it. These tubes are com- 

 posed of a felt-like mass of fine threads which are secreted by 



