LIFE IN A SPONGE 349 



which are almost contiguous, and is distinguished by the 

 three apical teeth of the telson. The third species, JEga 

 psora (Linn.), has the eyes well separated, and the inner 

 branch of the uropods emarginate on the inner side near 

 the apex. Because of the latter character Leach called it 

 emarginata, a name that would be naturally supposed to 

 apply to the telson, and which fortunately had to make 

 way to an earlier name. The fourth species, JEgamonoph- 

 thalma, Johnston, is not very happily named, since there 

 are very conspicuously two large elongate eyes, though 

 they happen to meet apically. The terminal segment of 

 the pleon has a central carina. It attains a length of more 

 than two inches. That which Johnston supposed to be a 

 variety of this species has been determined by Schiodte 

 and Meinert to belong to JEga Stromii. Twenty species 

 in all are distinguished by those authors, who point out 

 that the genera Pterelas, Guerin, and ^Egacylla, Dana, are 

 synonyms of JEya. -E'ja crenulata, Lutkeii, has been re- 

 corded from Scotland. The species ^Ega spongiophlla, 

 Semper, is notable for making its home in the beautiful sili- 

 cious sponge, Euplectella aspergillum, of the Philippines, in 

 which it can scarcely be expected to live by sucking the 

 juices of fish, but it is probably well supplied with food 

 from the other crustaceans and small marine animals 

 of various kinds which enter the glass-rope basket by 

 accident or design, and find themselves entrapped within 

 it in presence of a dangerous foe. ^Ega Schioedteana, 

 Bovallius, was described in 1885, jEga Loveni, Bovallius, 

 in 1886. ' 



Of Rocinela Schiodte and Meinert distinguish from 

 various parts of the world nine species, the type being the 

 British Rocinela danmoniensis, Leach. Rocinela signata, 

 Schiodte and Meinert, is found in the West Indies and 

 Central America. To one or other of these two species, 

 the other seven are said by Hansen to approach very 

 closely. He points out that both in sEga and Rocinela the 

 structure of the maxillipeds is probably adapted to pulling 

 apart the skin of a fish and clearing a space for the attack 

 of the mandibles. He considers Alitropus foveolatus from 



