CBUSTACEA. 135 



a very misnomer. The so-called happy families, which we sometimes 

 see in our streets, offer no such odd assemblages as we may often 

 find in and on the shell of a dead whelk. First we have the Hermit 

 Crab himself ; the margin of the shell is often tenanted by a species 

 of Anemone {Adamsiapalliata), while the rest of its surface is covered 

 by a growth of the curious and pretty little polyp, known as Hydrac- 

 tinia ecliinata. Nor is the Pagurus the only occupant of the shell. 

 ]Mi\ Grosse tells us of a co-tenant in the form of a beautiful Nereid 

 worm, which, like the preceding species, feeds on the crumbs which fall 

 from the rich man's table. " The soft and serpent-like Annelide," 

 Ave quote from Mr. Spence Bate (Zoologist, 1859, p. 6687), " smells 

 " the repast that the master of the house is enjoying, and, like a wily 

 " guest, takes care to be present at the meal, even though unbidden. 

 " See ! beneath the Crab the beautiful head glides out. While the 

 " self-confident owner is devouring one piece, and in his full enjoy- 

 " ment looking round and, perhaps, admiring the submarine scenery, 

 " the worm attaclis that which is in the other hand, and by little and 

 " little the Crab feels it going, and makes an eflbrt to stop it on the 

 " way ; but it evidently can be seen, by his manner, that he caiuiot 

 " believe that any one woidd be so rude as to steal his dinner out of 

 " his very mouth, and does not think much about the undevoiu'ed 

 " food, but which, nevertheless, is slowly, gradually, and surely taken 

 " away." 



To this interesting group must be added the Feltogaster Fagiiri, 

 wliich, when mature, has a regular oval form, and a reddish colour, 

 due to the numerous eggs it contains. So little does it, indeed, 

 resemble a Crustacean that we cannot wonder at the mistakes which 

 have been made concerning its true nature. Cavolini regarded it aa 

 a sort of animal-gall, not recognizing it as an entire animal, but 

 supposing that some other Crustacean deposited its eggs in the 

 Pagurus. Thompson first described it correctly, and recognized its 

 afiinities with the Lerneidae. Eathke at first placed it among the 

 Ti'ematodes, in which he was followed by Diesing and Dujardin, 

 though the latter, indeed, says that it " parait etre toute auti'e chose 

 " qu'un trematode." KJroyer expresses no opinion as to its afiinities. 

 Steenstrup classes it with Bopyrus, among the Isopods. Lilgeborg 

 looks upon it as a Cirrhiped. Professor Van Beneden places the 

 Sacculinidpe in his list of Crustacea, observed on the shores of Belgium, 

 immediately alter Lerneonema, and explains their homologies as 

 follows : — 



" Que Ton se figure, en cffet, des Nicothoe, dont les deux poches s'etendraient 

 tout autour du segment qui leur donne naissance, en d'autres termes, dont le 

 segment tout entier se prolongerait en arriere de manitere a enveloppcr I'abdomen 

 et la queue ; il y aura un orifice posterieur d'evacuation, un veritable cloaque 

 d'oiseau ; en supposant ensuite que la tete s' allonge comme dans les Lcrnea bran- 

 chialis et plonge de la menie maniere dans les chair, que les segments en arriere et 

 en avant s'eflacent pour ne plus laisser place qu'cn segment scxuci, nous aurons ime 

 idee de cctte transformation siugulierc d'un animal regulier ct symetriquc en sac 

 informe et gaine a ceufs." 



