570 
POLYPI. 
water, or fixed and congregated in cellular masses, composed of 
one substance, or aquatic substances ; polypi provided with nu¬ 
merous tentacula, but not entirely encircling the mouth.—The 
genera are, 64. Alcyonella; 65. Spongilla ; 66. Cristatella; 67. 
Difflugia. 
ORDER IV.—POLYPI DENUDATI. 
Polypi provided with tentaculi, and not congregated in a po¬ 
lypi ferous mass; greatly diversified in form, as well as in the 
number and situation of their tentacula; and either constantly 
or spontaneously fixed.—The genera of the order are, 1. Pedi- 
cellaria; 2. Coryne; and, 
Genus 3■ —HYDRA.— Lamarck. 
Generic Character. — With an oblong, linear body, or in the 
form of a reversed cone, narrowed below ; gelatinous, transpa¬ 
rent, and fixed spontaneously by the base ; having a terminal 
mouth, and a row of cirrous tentacula. All the species inhabit 
fresh water. 
ORDER V.—POLYPI CILIATI. 
Mouth provided with ciliated and gyratory organs, which agi¬ 
tate the water, but not fitted for seizing their food. 
Section I.— Rotiferi. 
Having one or many organs in a circular form, ciliated and 
rotatory at the orifice of the mouth.—The genera are, 1. Tubi- 
colarea; 2. Vorticella; 3. Urceolaria; 4. Furcularia; 5. Dra- 
chionus ; and. 
Genus 6.—FOLLIC ULINA.— Lamarck. 
Generic Character .—With a contractile oblong body, envelop¬ 
ed in a transparent sheath; mouth terminal and large, provided 
with ciliated rotatory organs. Inhabits the ocean. 
