60 ANIMAL PARASITES AND MESSMATES. 



A curious opinion, quite recently expressed by a 

 naturalist, Mons. Giard, and which is a sign of the times, 

 is that the Peltogaster of the Pagurus has become a 

 Sacculina on the crab ; the host having been transformed, 

 its acolyte has done the same thing under the same 

 influence. 



Professor Semper has also found among the Philip- 

 pine Islands, isopod crustaceans living as messmates 

 after the manner of the peltogasters. Two cirrhipedes 

 of the family of Peltogaster, the Sylon Hippolytes and the 

 Sylon Pandali, have been found by Mons. Sars under the 

 abdomen of the Pandalus brevirostris. 



There are cirrhipedes on the gasteropod molluscs. 

 The Concholepas Peruviana, that beautiful shell which has 

 long been considered a rarity in our collections, is fre- 

 quented by the Cryptophiolus minutus, only a sixth of an 

 inch in length. The Scalpella often inhabit the Sertu- 

 larise and other polyps; Oxynasps, Creusiee, Pyrgomie, 

 and IAihotryse inhabit corals. Certain kinds of sponges 

 are regularly invaded by the Acastse of Leach, eight 

 species of which are mentioned by Darwin. As we find 

 elsewhere parasites on parasites, here also we find mess- 

 mates on messmates ; on the common anatifa we per- 

 ceive other genera, and on the Diadema of the North 

 Pacific, we almost always see Otions and Cineras. The 

 Protolepas bivincta also, a fifth of an inch in length, lives 

 as a messmate in the mouth of the Alepas comuta; and 

 the Elminius of Leach also inhabits other cirrhipedes. 

 The Hemioniscus balani, which Goodsir had taken some 

 years ago for the male of the Balanus, is a messmate on 

 these cirrhipedes. Parasites also are found in mess- 

 mates ; the soldier-crab gives lodging to the sexual 



