FIXJID MESSMATES. 59 



account of which he will publish, together with the other 

 materials which he has collected during his passage across 

 the Atlantic. Mr. John Denis Macdonald found in 

 abundance on the branchiae of a crab in Australia, the 

 Neptunus pelagicus, which he places between the Lepas 

 and the Dichelaspis. 



The most singular, if not the most interesting of all 

 these cirrhipedes, are the Gallee, which appear under 

 the tail of crabs or the abdomen of paguri, and which 

 zoologists designate under the names of Peltogaster or 

 Sacculina. They are found in both hemispheres. The 

 recurrent development is so complete, that we can no 

 longer distinguish any organic apparatus unless it be 

 that of reproduction, and the whole body is a mere case 

 enclosing within its walls eggs and spermatozoids. We 

 see them very frequently under the abdomen of the crabs 

 of our coasts, or even on the segments of the bodies 

 of paguri. Mons. A. Giard has lately studied these 

 animals. It is during the coupling season, according to 

 him, that the Peltogasters establish themselves upon the 

 crabs. Professor Semper has brought back quite a collec- 

 tion of them from his voyage to the Philippine Islands, 

 and has entrusted them to one of his pupils, Dr. Kuss- 

 mann, for the purposes of study. "We heard him with great 

 interest, at the late Congress at Wiesbaden, explain with 

 remarkable clearness the results of his learned and 

 conscientious observations. We do not think that we 

 shall be wrong in adding that, for a long time, we shall 

 see nothing better or more complete on this subject. All 

 those cirrhipedes which adhere by their head to the skin 

 of their host, by means of filaments, are now designated 

 by the name of Rhizocephala. 



