)
" 5. _Spongida_ (Sponges).
CLASS III. INFUSORIA.**
SUB-KINGDOM II.--COELENTERATA.
Animal simple or compound; body-wall composed of two principal
layers; digestive canal freely communicating with the general
cavity of the body; no circulating organs, and no nervous system
or a rudimentary one; mouth surrounded by tentacles, arranged,
like the internal organs, in a "radiate" or star-like manner.
CLASS I. HYDROZOA.
_Sub-class_ 1. _Hydroida_ ("Hydroid Zoophytes"). _Ex._
Fresh-water Polypes,** Pipe-corallines (_Tubularia_), Sea-Firs
(_Sertularia_).
_Sub-class_ 2. _Siphonophora_** ("Oceanic Hydrozoa").
_Ex_. Portuguese Man-of-war (_Physalia_).
_Sub-class_ 3. _Discophora_ ("Jelly-fishes"). Only known as
fossils by impressions of their stranded carcasses.
_Sub-class_ 4. _Lucernarida_ ("Sea-blubbers"). Also only
known as fossils by impressions left in fine-grained strata.
_Sub-class_ 5. _Graptolitidoe_* ("Graptolites").
CLASS II. ACTINOZOA.
_Order_ 1. _Zoantharia_. _Ex_. Sea-anemones**
(_Actinidoe_), Star-corals (_Astroeidoe_).
_Order_ 2. _Alcyonaria_. _Ex_. Sea-pens
(_Pennatula_), Organ-pipe Coral (_Tubipora_),
Red Coral (_Corallium_).
_Order_ 3. _Rugosa_ ("Rugose Corals").
" 4. _Ctenophora_.** _Ex_. Venus's Girdle (_Cestum_).
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