430 POLYPI. 
latinous, diaphanous, and move nearly in the manner of a Medusa. 
The receiver produces from the bottom of its cavity a chaplet which 
traverses a semi-canal in the received, and appears to be composed of 
ovaries, tentacula, and suckers, like those of the preceding genera. 
This genus has been divided by Messrs. Quoy and Gaymard ac- 
cording to the relative form and proportions of the two individuals. 
Thus in 
DienyeEs, proper, 
The two individuals are almost similar and pyramidal, with some 
points round their aperture, which is at the base of the pyramid *. 
In Capes the received is still pyramidal, but the receiver is very 
small and square. 
In Axzyues the received is oblong or oval, and the receiver some- 
what small and bell-shaped. 
In Cusorpes the received is small and bell-shaped, the receiver 
much larger and square. 
In Navicuxa the received is bell-shaped; the receiver is large, but 
has the figure of a wooden shoe f. 
There are several other combinations. 
CLASS IV. 
POLYPI (a). 
Our fourth class of the Radiata or Zoophytes has been thus named 
because the tentacula which surround their mouth give them a slight 
resemblance to an Octopus called Polypus by the ancients. The 
number and form of these tentacula vary. The body is always cy- 
lindrical or conical, frequently without any other viscus than its ca- 
vity; and frequently also with a visible stomach, to which adhere intes- 
tines, or rather vessels excavated in the substance of the body, like 
those of the Medusve; in this latter case we usually find ovaries also. 
Most of these animals are capable of forming compound beings, by 
shooting out new individuals, like buds. They also, however, propa- 
gate by ova. 
* Bory Saint Vincent, Voy. aux Isles d’Afrique. 
+ See the Mem. of MM. Quoy and Gaym., Ann. des Sc. Nat., X. 
{> (a) This class of animals, although nearly at the end of the series, is one of the 
largest, and certainly the most singular of the whole. Such is the enormous accu- 
mulation of the stony envelopes formed by them in certain seas, that islands are pro- 
duced, coasts extended, and harbours blecked up by them. ‘The late lamented M. de 
Lamarck has even hazarded the idea, that the calcareous strata of the globe may 
haye been produced by them. Polypi were formerly considered as stony plants. 
Tmperati (1699) was the first who doubted their vegetable nature, and Trembley’s 
observations on the Hydra (1740) put the question at rest. Since that period, our 
knowledge of them has been considerably inereased by the labours of Ellis, Boccone, 
Cayolini, Lamouroux, &¢. &c.— ENG, Ep. 
