GLOSSARY OF SCIENTIFIC TERMS.
Extracted principally from Professor Owen's learned work entitled, "Lectures on the
Comparative Anatomy and Physiology of the Invertebrate Animals."
Ambulacra (L. ambulacrum, an avenue, or place for walking). The perforated series of plates in the shell of the Sea-star, or Sea-urchin, through which the sucking-feet are protruded.
Acalepha (Gr. akalephe, a nettle). The class of radiated animals with soft skins which have the power of stinging like a nettle. Commonly called Sea-nettles or Jelly-fish.
Actinæ (Gr. aktin, a ray). The genus of Polypes which have many arms radiating from around the mouth.
Alternate generation. That modification of generation in which the young do not resemble the parent, but the grandparent; so that the successive series of individuals seem to represent two species, alternately reproduced, in which also parthenogenesis alternates with the ordinary engendering by impregnation.
Algæ (sea-weeds). A large class of cryptogamic plants inhabiting salt and fresh water.