HABITS OF THE FOUR-HORNED SPIDER-GRAB. 255 



readily eaten. In the case of the first-mentioned tube the 

 Spider-Crab dropped most, perhaps all, of it as it bit through it. 

 After the worm had been taken from the second tube, the latter 

 was cut up into several short lengths and thrown back into the 

 aquarium. They lay untouched on the floor of the tank for 

 three weeks, and it may therefore be concluded that the Spider- 

 Crab will bite through the tube only in order to reach the worm, 

 and not in order to eat the tube itself. I have seen a Spider- 

 Crab tearing and eating two ascidians, each of which was about 

 an inch and a quarter in length. 



On the night of February 17th-18th, 1915, a number of 

 bright vermilion eggs were laid on one of the horizontal rocks in 

 the aquarium containing the three female Four-horned Spider- 

 Crabs mentioned above. The tiny eggs were not in a mass, but 

 were thinly spread, and gave, when I first caught sight of them 

 on the morning of the 18th, the impression that some paint had 

 been splashed over the rock. I estimated their number at about 

 2500. One of the Spider-Crabs, which may or may not have 

 been the mother, was standing over the eggs and shovelling 

 them into her mouth with her claws in her usual slow and 

 deliberate manner. About an hour afterwards another individual 

 joined the first and also began to eat the eggs. The Spider- 

 Crabs were driven away, but they returned later. The eggs 

 rapidly dwindled in number under these attacks, and on the 

 22nd there were only a few, which had fallen into holes and 

 cracks, to be seen. The worm-shaped faeces of the Spider-Crabs 

 were tinged with]vermilion during these few days. About two 

 or three hundred more eggs were laid in the same tank on the 

 night of February 24th-25th, but they were all eaten by the 

 Spider-Crabs, and none were to be seen by the 27th. On 

 the night of May 14th-15th, about a thousand vermilion eggs 

 were laid, and these also disappeared speedily, though in this 

 case I did not actually see the Spider-Crabs eating them. The 

 two last lots of eggs were littered over the rocks, as the first had 

 been, and were not in masses. I examined each female when- 

 ever eggs were deposited, carefully turning back the abdomen 

 in order to do so, but in no case did I find any eggs retained 

 between the thorax and the abdomen. On March 26th the 

 same Four-horned Spider-Crabs were offered a mass of eggs 



