3o6 THE COURTSHIP OF ANIMALS 



two ago Fairy Shrimps were found in abundance in rain 

 pools at Eton, and some, indeed, were discovered swim- 

 ming gaily about in a rain-filled cart-rut ! 



Another very singular Crustacean, known as Apus, 

 bears a curious superficial likeness to the King Crab 

 (Limulus), having a large back-shield and a long tail. 

 This little creature, a giant compared with his nearest 

 relations, is an inhabitant of wayside ponds and ditches. 

 Thousands of females may be taken for years in suc- 

 cession without the advent of a single male. Then, for 

 some strange reason which we cannot even guess at, 

 males appear. Like its freshwater cousin, the Fairy 

 Shrimp, Apus can withstand drought : its favourite haunts 

 may be transformed into sun-baked hollows, but with a 

 heavy fall of rain and a few hours' soaking the eggs left 

 by dead females develop, and once more the pool and 

 its inhabitants are established again. Having regard to 

 the extraordinary vitality of these small creatures, it is 

 curious that they should ever disappear from their favoured 

 haunts. But they do. Not many years ago Apus could 

 be found in abundance in many parts of the South of 

 England. It is now extinct ; its last resorts were the 

 ponds at Hampstead : now one may search in vain for 

 them. " No British specimens," remarks Dr. Caiman, 

 a great authority on the Crustacea, " had been recorded 

 for over forty years, and the species was believed to be 

 extinct in this country, when it was found in 1907 by 

 Mr. F. Balfour Browne in a brackish marsh near South- 

 wick, in Kirkcudbrightshire." These had probably 

 developed from eggs accidentally transported by some 

 bird from the Continent. The extinction of the race 

 throughout the British Islands can only be attributed 

 to the too long absence of males, and the consequent 



