BRITISH STALK-EYED CRUSTACEA. 387 



series, and that the crab -shaped forms were developed through 

 the Lithodes or Dromia types, whilst the lobster-shaped forms 

 obtained through that of Galathea or Munida ; at any rate, the 

 need of an artificial protection, such as the Paguridce absolutely 

 require for their very existence, implies a condition of existence 

 so hazardous and precarious, that a state of things in which a 

 naturally protected abdomen replaced one of so delicate and 

 unguarded a nature would be far more conducive to the develop- 

 ment of the species, or rather of allied species generally. 



Another remarkable feature in connection with the Paguridce 

 is that, so far as is known, almost their sole protection has been 

 the dead shells of Univalve molluscs. These molluscs would 

 therefore have been in existence prior to the period when the 

 defenceless condition of the Paguridce required such protection. 

 From this it would seem as if this group were really a degenerate 

 form of the Crustacea, considering that the latter are older 

 geologically, and therefore also in point of development, than the 

 Gastropods, the highest forms of the Testaceous Mollusca. 



In describing the Paguridce we shall only enumerate the 

 generic features when treating of Pagurus Bernhardus, and refer 

 to the specific characteristics only of the rest of the species, and 

 the points of identification. 



Pagurus Bernhardus, Linne. 



This is the largest, commonest, and therefore the best known 

 species of this genus ; in fact, it is the only one known, even to 

 many observing individuals, and is therefore called " The Hermit 

 Crab." The species is also known by the name of " Farmers" in 

 Essex, and on the south coast are called " Soldiers." 



The carapace is smooth, divided behind the cephalo-thoracic 

 portion into two lobe-like portions; it has a short stunted 

 rostrum. The eyes are fixed on stout short peduncles, and the 

 antennae are long and well developed. The anterior pair of legs 

 are massive, unequal, and very roughly granulated ; the next two 

 pairs are also granulated and tapering to a sharp-pointed terminal 

 joint, and the last two pairs are rudimentary. There are also 

 pseudo-swimmerets, which, in the case of the female, are the 

 processes to which the ova are attached. The abdomen is, as we 

 have said, a membranous sac, but it is furnished with a small set 

 of tail-plates, armed with powerful hooks, which serve as anchors 



