EXPLANATION OF PLATE XVI. 



CRUSTACEANS. 



Fig. 1. A. KING CRAB, MOLLUCCA CRAB or HORSE FOOT; a, the opening 

 through which the animal emerges when casting off the old shell ; b, 

 small feet in front of the mouth, considered by some naturalists as 

 antennce, or feelers ; c, the other five pair of true feet surrounding the 

 mouth, used for walking and mastication ; d, triangular shield cover 

 ing the body to which the five pair of false feet or swimming legs are 

 attached ; e, long pointed tail. 



B, Branchipus stagnalis, in road-side ditches and cart-wheel ruts. 



Fig. 2a. Sow BUG, or WOOP-LOUSE ; b, Limnoria terebrans ; c, Fluvicola ; 

 1, under side; 2, upper side, d, Trilobite, found only in a fossil 

 state. 



Fig. 3. CRAW-FISH, or FRESH-WATER LOBSTER; (Astacus fiuviatilis ;) a, 

 five pair of true feet ; b, inner antennae, supposed^ to be the organs 

 of hearing ; c, outer and longer antennae, organs for smelling ; d, 

 five broad caudal plates, by which the animal is assisted to dart about 

 so rapidly. 



Fig. 4. A, DUCK BARNACLES, Pedunculated or Stalked Cirripedes ; a, pe 

 duncle or stalk by which they are attached to submerged substances 

 after the third moult; b, shell of five or more valves; c, six pair 

 of feathery cirri for obtaining its food ; B, Acorn Barnacles, (Ses 

 sile Cirripedes,) composed of six valves, with an operculum or cover 

 of four pieces, between which the curly tentaculae protrude. 



ANNELIDANS, Or WORMS. 



Fig. 5. Vermilia, (a,) lives in an irregular twisted tube, attached by its 



whole length to shells, stones, &c. 

 Fig. 6. Sea Centipede, or Nereis; organs and gills distributed throughout 



the body; each of its numerous feet has two tubercles, two bundles of 



bristles, and a cirrus above and beneath. 



REP-^LOODED WORMS. 



Fig. 7. A. Medicinal Leech ; a, the mouth, with three sharp teeth disposed 

 in a triangle ; no distinct head ; moves by the adhesion and detach- * 

 ment of the sucking disks at each extremity. 



B. Earth or Angle Worm ; eight retractile bristles on the under side 

 of each ring, assisting in their contractions and dilations, enabling it to 

 creep at a pretty good pace ; no distinct head, but the fore part, (a,) 

 acts as a sort of awl in penetrating the earth. 



ENTOZOA, INTESTINAL, Or WHITE-BLOODED WORMS. 



Fig. 8. Fluke, Distoma; a, upper side; b, under side; an inch long; 

 two eyes; two suckers; infests the liver of animals. In sheep it pro 

 duces or aggravates the disease called the rot. 



Fig. 9. Tape worm ; flat or ribbon-like : sometimes 60 or 100 feet long, 

 with 500 divisions, each of which adheres to the intestine by a strong 

 sucker, and may become a separate and perfect animal. The seg 

 ments diminish in size so as to form a thin neck with a small globose 

 head, (a,) mouth very indistinct. 



