204 NATURAL HISTORY. 



moreover, under the tail of the larger ones there is a great mass of fat, which, when melted, 

 sometimes yields as much as a quart of limpid oil. It has been stated by some that Birgus latro 

 crawls up the cocoa-nut trees for the purpose of stealing the fruit. I very much doubt the possibility 



of this, but with the Pandanus * the task would 



be very much easier. I understood from Mr. 



Leisk that on these islands the Birgus latro 

 lives only on the nuts which fall to the ground." 

 (C. Darwin : " A Naturalist's Voyage Round the 

 World.") 



The friendship interested or otherwise 

 cemented between Soldier Crabs and Sea Anemones 

 is very remarkable. One Sea Anemone, the Sagartia 

 parasitica, seems to be on very friendly terms 

 with the Hermit Crabs, always selecting for its 

 place of attachment the dead shell of some whelk 

 tenanted by one. The Crab who sustains the 

 Fig. 20. HERMIT CRAB (Ccnobita) IN SHELL. honourable office of porter to this Anemone is in- 



(Afler Morse.) variably the Pagurus b&rnliardus. 



Prof. Dana mentions another Actinia from the China Seas the Cancrisocia expansa which 

 associates with Dorippe (an anomourous Crab), who holds the Actinia, on its back with its two 

 posterior pairs of legs. 



DECAPODA MACROURA. (LOBSTERS.) 



The Macrourous (or large-tailed) type of the order (DECAPODA) is represented by the Lobster, 

 essentially an aquatic form, and possessed of great powers of locomotion. The hinder segments of 

 the body (termed the abdomen) are very much developed, and of nearly equal growth, being also 

 compressed at the sides, so as to be somewhat cylindrical in form. They present a well-marked 

 difference from the tail of the Crab (BRACHYURA), in which the segments are short and flattened, and 

 expanded laterally. The abdomen in the Lobster is also terminated by a broad swimming tail. 



The members of this division are very abundant numerically in both marine and fresh water. t 



The Common Spiny Lobster (Palinurus wdgaris) has thick, extremely long, and stiff external 

 antennae, the basal joints of which are very large, and unite to form the front of the mouth. The 

 three following joints are large, thick, and spinose. Each antennule has three very long and slender 

 cylindrical basal joints with two small feelers at its tip. The outer jaw-feet are formed like feet. 

 The true walking legs are all one-toed at their extremity. The first paii% however, which are thicker 

 and shorter than the others, has a spine on the border of the last joint but one against which the last 

 joint shuts, thus forming a rudimentary chela or nipper. The carapace is extremely rugose, being 

 covered with spines and tubercles. The body segments are large, and the tail-fins well developed for 

 swimming. The family of the Palinuridce are of very ancient origin, going back in geological time 

 to the Solenhofen rocks (Oolitic age). Only one genus now survives. 



The genus Palinurus comprises several large edible species, one of which, the Common Spiny 

 Lobster (P. vulgaris), inhabits the English western coasts, and is brought thence in large quan- 

 tities to London. They are found chiefly on rocky coasts, and are often taken in the crab-pots- 

 Great numbers of this Lobster are also eaten in France. Its flesh is much esteemed, though by some 

 considered inferior in flavour to that of the Common Lobster (Homarus vulgaris). It reaches about a 

 foot in length, and sometimes as much as eighteen inches. The antennae are very long, just twice 

 the length of the entire body. The carapace is thickly covered with spines of various sizes, and all 

 the species have a large spine over each eye. 



* Proceedings of the Zoological Society, 1832, p. 17. 



t In his book on the Crayfish, Prof. Huxley mentions, that, in Tasmania, the genus Engceus (one of the Parastacidce), a 

 small kind of Crayfish, lives habitually on land in burrows, which they excavate in the soil (p. 306) and Parastacus 

 pilimanus, from Santa Cruz, in the upper basin of the Rio Pardo, an affluent of the Jacuhy, was obtained " by digging it out 

 of holes in the ground " (p. 308). So that the Crayfish is an exception to the general rule, that all the Macroura are truly 

 aquatic in their habits, and that none are terrestrial. 



