No. 4-] AMPHITHOE LONGIMAXA SMITH. 175 



a nest Amphithoe is driven out only with difficulty. A mem- 

 ber of its own species that approaches is grabbed at and usually 

 driven off, and the creature appears to be on the alert to keep 

 out all intruders. The approach of a more formidable-looking 

 object causes the animal to retreat farther back into its nest. 

 If the antennae are stroked with a needle, a sudden somersault 

 will be executed and the head will appear at the other end of 

 the nest. Then it usually requires quite a series of pokes to 

 make the creature quit the nest entirely. The instinct to 

 remain in the nest when danger threatens presents a marked 

 contrast to the quickness with which flight is made when the 

 animal is roaming free. 



A new nest is constructed in a remarkably short time, often 

 in less than a half hour. If a few specimens be placed in a 

 dish of sea water containing a little seaweed, nests will be 

 woven on the seaweed and on the lower surface of the dish, 

 and in a short time the number of nests may greatly exceed 

 the number of specimens. Those localities are chosen which 

 give the animal a maximum of contact with solid objects. In 

 dishes in which specimens were kept I have nearly always 

 found several nests along the angle between the bottom and 

 sides, although the seaweed kept in the dishes afforded locali- 

 ties better adapted for concealment. The choice of a spot for 

 a nest is apparently largely a matter of thigmotaxis. When 

 the animal remains in a spot for some time, the nest-building 

 activities begin, and where contact with different sides of the 

 body is secured, as between the branches of seaweed, in the 

 wrinkle of an Ulva frond, or in the angles of a glass dish, it 

 remains quiet. If Amphithoe is observed while constructing 

 its nest, the first and second pairs of pereopods will be seen to 

 be busily engaged in moving back and forth from point to 

 point along the surface on which the web is being laid down. 

 The first and second pereopods contain large glands which are 

 connected with a duct which opens at the tip of the claw. The 

 material for the web is secreted by these glands and probably 

 hardens soon after its emergence, like the web of a spider. A 

 very fine thread of web may frequently be seen passing out 

 from the small opening at the tip of the claw. As the tip of 



