. A text-book of agricultural zoology. Zoology, Agricultural; Zoology, Economic. 98 CRUSTACEA. pair of antennas. Abdomen composed of many segments. Legs very numerous, always more than eight pairs. Tracheal respiration. i. InsectaâHead, thorax, and abdomen distinct. One pair of antennae. Eyes both simple and compound. Legs always six in number. No appendages of locomotion ever on the abdomen. Two pairs of wings generally present. Respiration tracheal. Crustacea. The Crustacea arc chieflj' aquatic arthropods. Some few species live in damp earth and in damp general surroundings: these belong to
. A text-book of agricultural zoology. Zoology, Agricultural; Zoology, Economic. 98 CRUSTACEA. pair of antennas. Abdomen composed of many segments. Legs very numerous, always more than eight pairs. Tracheal respiration. i. InsectaâHead, thorax, and abdomen distinct. One pair of antennae. Eyes both simple and compound. Legs always six in number. No appendages of locomotion ever on the abdomen. Two pairs of wings generally present. Respiration tracheal. Crustacea. The Crustacea arc chieflj' aquatic arthropods. Some few species live in damp earth and in damp general surroundings: these belong to the order l8oj)oda. The order Isopoda contains the Wood-lice : they may be told by the equal and synmietrical feet or legs, whilst in the others, such as the Crab and Lobster, the claws are asymmetrical. There are three species injurious to horticulturists generally, all of which belong to the family Oniscidce. The Oniscidfe belong to the second tribe of Isopoda, called the Euisopoda, which have the body made up of seven free thoracic segments and the same number of paired appen- dages. The abdominal feet are so land Isopods, with the endopodites Fig. ^f (.|jg abdominal feet formed into A, Armadillo vulgari,s; B, Por- i i, ⢠ii Ti - ^ j. ceilio scaber; c, A vulgaris ,â d, branctiice, the exopodites into protec- antenna of Onisous; E, antenna j-- ,â l,iâ,.âl ,,iâ(- ji i 'j ofPorceiiio. tive lateral plates on the outside. Peculiar modifications may be seen on the two front abdominal feet, which are provided with special sacs to contain air. The three common species are Oniicus asellus of Linnreus, PorceUlo scahcr of Latreille, and Armadillo vulgaris of Linnaaus (fig. 37). Tbey are popularly called Monkey-peas or Slaters in Britain, the Cow-bugs of America; perhaps the term Wood-louse is that most usually employed. Onisciis asellus is omnivorous, eating animal and vegetatle. modified as to form branchial lameUse. (5=t^ «b: -jjjg Oniscids or Wood-lice (fi
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1899
