88 . THE VICTORIA^ KATDRALIST. 



whole body and limbs like a suit of armour, and so it is called, in 

 scientific parlance, an exo, or outside skeleton, although it is true 

 also that it is found to send certain processes of its substance into 

 the interior of the body for the support of the soft parts within. 

 The Crustacea nearly all inhabit either the sea or fresh water, and 

 breathe by gills, or else in the lower forms and in the embryonic 

 stages of the higher ones by the thin membraneous sides of the 

 body. 



The special order of Crustacea under which crabs are ranged is 

 the "Decapoda," so called from the Greek ^eKa==10, and ttous, ttoSos 

 =a foot, because the ambulatory or walking feet are in 5 pairs, and 

 crabs belong to that section of the order called the " Brachyura," or 

 short-tailed crustaceans, because they have the abdomen, or what is 

 popularly termed the " tail," short and rudimentary, a mere hard, 

 thin, flat-jointed appendage, which is kept folded tight under the 

 body so that you can scarcely see it, very much in the same way as 

 our humorous Professor used to say that a frightened poodle carries 

 his tail when under chase by a larger dog ; whereas the " Mac- 

 rara,'''' or long-tailed crustaceans, such as lobsters, crayfish, prawns, 

 and shrimps have the tail large and extended, and mth terminal 

 flaps for use in swimming, and the " Anomura^'' or irregular-tailed 

 crustaceans, such as hermit or soldier crabs, have the abdomen soft 

 and furnished with a sucker or a forceps at the end, by which to 

 adhere to the interior of cast-off whelk or spindle shells in which 

 they live. Although crabs carry their tails in a somewhat undig- 

 nified way, they are by far the most highly-organised and thorough- 

 bred group of the Crustacea — in fact, they are the aristocrats of their 

 class, who are getting advanced beyond such vulgar things as tails, 

 hence, no doubt, they hide them out of sight as though they were 

 ashamed of them. The body of crabs, like those of lobsters and 

 crayfish, consists of 21 joints, or somites, as they are called — 7 for 

 the head, 7 for the thorax, and 7 for the post-abdomen or tail. 

 Huxley adopts a somewhat different arrangement, viz., 6 for the 

 head, 8 for the thorax, and 6 for the tail — 20 in all, probably a 

 more accurate view as far as the segments of the head and 

 thorax are concerned, but I follow the opinion of older naturalists 

 in counting 7 segments in the tail, i.e., including the telson 

 or end piece as a distinct segment, for the simple reason that 

 it is pierced as the others by the intestinal canal. The joints 

 of the head and thorax, however, are united more or less 

 into a single mass, called the "cephalo-thorax," by a dorsal 

 shield or covering, called the " carapace," which in crabs is 

 very large and depressed, the line of division between the head 

 and thorax being only slightly marked on the carapace by the 

 neck suture, but all the joints being perfectly distinct on the under 



