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Show 386 ACALEPIIA.. It is directly after these hydrostati·C Acalepha that we may place the DIPHYES, Cuv · d'fferent individuals are always A very s.m gul ar genu s ' where two '1t £the other, but susceph'b le d in a caVl Y 0 found together, one encase . the life of either. They are of being separate d W'lt bout destroymg arly in the manner o £ a M e- . h s and move ne . l gelatinous, d1ap anou ' f the bottom of its caVIty a chap et . produces rom b dusa. The recewer . h eceived and appears to e com-emi- canal m t e r ' d' which traver~es as d ckers like those of the prece mg posed of ovaries, tentacula, an su ' genera. . . d d by Messrs Quoy and Gaymard ac- This genus has ~een dtvl e d ro ortions of the two individuals. cording to the relative form an p p Thus in DIPHYES, proper, . . . lmost similar and pyramidal, with Rome The two mdlVlduals are a h' h . t the base of the pyramid(l). d h . erture w lC lS a points roun t eu ap. . .11 . idal but the receiver is very In CALPES the received lS stl pynm ' small and square. . . bl r oval and the receiver some- In ABYLES the received lS o ong o ' what small and bell-sha?ed. . 11 d bell-shaped, the receiver In CuBoiDES the received IS sma an much larger and square.' d. b 11-shaped; the receiver is large but In N A vxouLA the receiVe IS e has the figure of a wooden shoe~2) .. There ·are several other combmatlons. . . v x Isles d' Afrique. (1) Bory Samt-Vmcent, oy. au . Ann des Sc. Nat., X. (2) See the Mem. of MM. Quoy and Gaym., . 387 CLASS IV. POLYPI(l). Our fourth class of the Radiata or Zoophytes has been thus ~amed 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 rs always cylindrical or conical, frequently without any other viscus than its cavity, and frequently also with· a visible stomach to which adhere intestines or rather .vessels' excavated in the substance of the body like those of. the Medusre ; 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, how· ever, propagate by ova. ·,J (1) 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 :s the en01·mous accu~ mutation of the stony envelopes formed by them in certain seas, that islands are produced, coasts extended, and harbours blocked up by them. The late lamented M. de Lamarck has even hazarded the idea, that the calcareous strata of the globe may have been produced by them. Polypi were formerly considered as stony plants. Imperati ( 1699) was the first who doubted their vegetable nature, and Trem. bley's observations on the Hydra. (1740) put the question at rest. Since that period, our knowledge of them has been considerably increased by the labours of Ellis, Boccone, Cavolini, Lamouroux, &c. &c. .O.m. Ed. |