UMBELLULARIA. % POLYPI. 419 



I. POLYPI NAT ANTES. Tentaculated polypi, united in a 

 common fleshy body on an axis, free, and floating in the water. 



II. POLYPI TUBIFERI. Tentaculated polypi, united in a 

 common fleshy body, destitute of solid internal axis, and cover- 

 ed with tubiform cylinders. 



III. POLYPI VAGINATI. Tentaculated polypi, constantly 

 fixed in an inorganic covering, and forming in general compound 

 animals. 



IV. POLYPI DENUDATI. Tentaculated polypi, not forming 

 a common envelope, fixed either constantly or spontaneously. 



V. POLYPI CILIATI. Polypi destitute of tentacula, but with 

 vibratile ciliae at or near the mouth. 



The habitations of the Polypi, or the common masses formed 

 by their united labours, are more or less calcareous or stony, 

 from the madrepores, of a substance as consistent as shells, to 

 the fibrous or membranous horny envelope of the sponge. Be- 

 tween these extremes are found every variety of consolidation 

 and consistence ; but all are formed by animals approaching to 

 one another in their general organization. Polypi are reprodu- 

 ced by ova, or a separation of parts natural or accidental. Their 

 food is chiefly animal, derived, in the case of the smaller species, 

 from the infusory animalculae which inhabit the waters. 



ORDER I. POLYPI NATANTES. 



Polypi united in a common body, free, elongated, fleshy, enve- ' 

 loping an inorganic axis, cartilaginous, osseous, or stony ; ra- 

 diated tentacula around the mouth of each polypus. 



The animals of this order possess a common body, distinct from that of the indivi- 

 duals, but in which they necessarily participate. This common body has the appear- 

 ance of a naked fleshy mass, which is common to all the polypi which protrude 

 from its surface ; and in the centre is an inorganic axis, resulting from some de- 

 position of the animals, in the same manner as the outer covering is formed in the 

 other orders. According to Cuvier, the alimentary canal of the genus Veretlllum is 

 furnished with many vascular ccecums spread over the fleshy mass, and by which the 

 polypi communicate. Some of these compound animals float freely in the water, and 

 others remain at the bottom in the mud or sand. Many of them are phosphorescent. 



Gen. 1. UMBELLULARIA, Lam. Pennatula, Lin. 

 Body free, consisting of a long simple stem, with a bony inar- 

 ticulated axis, enveloped by a fleshy membrane ; polypi large, 

 united in an umbellate form, with each eight ciliated tenta- 

 cula. 



