KOTES OX THE PAIIUXG OF TSE LAND-CRA13. 1 73 



15. Notes on the Pairino- of the Land-Crab, Cardisoma 

 armatam. By Mi»s L. E. Oheesman, K.E.S., F.Z.S., 

 Curator of Insects to the Society. 



[Received March 5, 1923 : Read March 6, 1923.] 



As nothing is recorded of the life-history of this species, it 

 was desiiuble to encourage the pairing of those specimens under 

 observation in the Insect House. Few females, however, have 

 been collected. Of the three consignments of these crabs kindly 

 sent to us by Captain Armitage from the neighbourhood of the 

 mouth of the River Gambia, the first, received in September 



1921, consisted of nine males; the second, received in March 



1922, consisted of fourteen males, and two small females which 

 died in less than a fortnight. The third consignment, received 

 in July 1922, consisted of thirteen males and two females, one 

 small and one of medium size. 



The larger female was placed with a male in a separate bay 

 containing sand and coarse gravel a foot and a half in depth, and 

 a tank of fresh water. The male dug a vertical burrow in one 

 corner, and the female dug a horizontal tunnel in the centre of 

 the bay. The male fed in the daytime, but the female was 

 rarely seen until an hour after closing-time. Both crabs took 

 boiled rice, boiled and raw potatoes, and dry leaves ; the male 

 (but not the female) fed also on pieces of raw meat and fish. 



In the first v/eek of August the female's tunnel had a second 

 opening on the side nearest tlie male's burrow, and for the next 

 fortnight they shared the tunnel ; neither of the crabs were seen 

 in the daylight during that time, unless disturbed. At the end 

 of a fortnight the male dug a nev/ burrow, and was not after- 

 wards found in the female's burrow. 



On August 26th the male was removed, and two tanks were 

 placed in the bay, one of fresh water, the other of sea-water 

 renewed weekly. The female only emerged at night after that 

 date. All the females we have had under observation have been 

 reluctant to show themselves above ground before dusk ; this 

 probably accounts for their being less easy to procure than the 

 males. This female came out every three or four nights to feed 

 and bathe, but any movement, or the switching on of the electi-ic 

 lio-hts, caused her to retire to her burrow ; if she was out on the 

 other nights she did not feed, for the food was untouched. She 

 was only twice seen in the sea-water tank. If she did not 

 appear for three days the burrow was opened, otherwise she 

 was not disturbed. 



On September 18th, 1922, the crab was discovered to be in 

 spawn. 



On September 22nd a portion of the eggs was severed from 

 her and sent to Professor McBride at the Imperial College of 

 Science. The crab cast the rest of the eggs that night. 



