62 INVERTEBRATE ANIMALS. 



Province ARTHROPODA. 



upQpov, a joint; ttouc, a foot. 

 Animals with jointed limbs articulated to the bodj'. 



This great Province vastly outmimiers in species the total of the 

 preceding invertebrate Provinces, and exceeds them in the interest 

 of its annals. The gathering up of several body-segments, somites, 

 to form a true head, here first appears, and ivith it apparently 

 a capacity for the higher orders of instinct. Pri'figured in Vermes, 

 this arrangement attains perfection by multitudinous steps and 

 very sloiv degrees. The term Aethropoda is retained as a con- 

 venient designation, but is inferior to Anndlosa in expressing the 

 chief character of the present Sub-kingdom. 



Class CRUSTACEA. Crmta, a crust. 

 Kespiration generally by gills. Antennae, two pairs. 

 Jointed appendages, more than eight. The body of a typical 

 Crustacean is made up of about twenty-one segments or 

 somites, often nearly equally distributed between the head, 

 the thorax, and the abdomen. 



The general arrangement of the Class is in accordance loith the 

 ^^ Histoire Naturelle des Crustaces," par M. Milne Edwards; but 

 advantiige has frequently been taken of the great work on the same 

 subject by James Dana, of the United States Exploring Expedition^ 

 This ivork is a monograph of surpassing excellence. 



Sub-class CIRRIPEDIA. Cirrus, a curl ; pes, a foot. 



In the larval state the Cirripedes are free and loco- 

 motive : subsequently two of the larval antennae dis- 

 charge a kind of glue, by which the head of the animal 

 becomes permanently attached to some solid object. 



Group 159. — Family BALANID^ and allies. (SaXavoc, an 

 acorn. In the family of Sessile-cirripedes, or Acorn- 

 shells, the head of the animal is fixed to the centre of a 

 shelly plate, the basis of a conical shell made up of 

 several pieces and open at the top when not closed by 

 the pyramidal operculum. To the thorax are attached 



