POLYPI, 119 



Order Onchophora. 

 Body depressed, subarticulate. Mouth provided with hooks. Anus 

 distinct. 



Genus : Linguatula. 



LECTURE VII. 



POLTPL 



Hydrozoa and AntJiozoa. 



The two great divisions of Cuvier's Zoophytes, viz. the Infusoria 

 and Entozoa, which have hitherto engaged our attention, approxi- 

 mate to the vermiform type ; and each ascends by rapid steps to the 

 confines of the articulate province. The remaining classes of the 

 Zoophytes are constructed on the radiated type ; and some of them, 

 as the Bryozoa and Acalephce, conduct to the molluscous series- 

 To-day I have to request your attention to the history of a race 

 of animals almost as widely diffused, almost as numerous, and some 

 of them hardly less minute than the Infusoria, with which we com- 

 menced the survey of the vermiform zoophytes. Our present sub- 

 jects form at least three classes of radiated zoophytes, which have 

 been grouped together under the common name oi Polypi, on account 

 of their external resemblance to the many-armed cuttle-fishes, which 

 were so denominated by the ancient Greek naturalists. But the 

 knowledge of the organised beings now called Polypi, as members 

 of the Animal Kingdom, is of comparatively recent introduction : it 

 cannot be dated further back than the time of Imperato* and 

 Peyssonel.t Amongst those naturalists who have subsequently 

 contributed to improve and extend the history of the Polypes, our 

 countryman Ellis J will always take a high rank. 



A polype generally presents a soft cylindrical oval or oblong body, 

 with an aperture at one of its extremities, which is suiTounded by a 

 coronet of long tentacula. In most of the class, this aperture leads 

 to a simple digestive cavity, consisting of a stomach without intestine. 

 In the highest organised group, the digestive sac is prolonged into 

 an intestinal canal, which is bent upon itself, and terminates by a 

 distinct anus opening upon the external surface. The organisation 

 of the polypes is in general simple ; their faculties are limited ; 

 and the vital phenomena, save those of irritability and contractility, 

 are inconspicuous. Nevertheless the influence of the combined 



* XCV. (1599). t XCVL (1723 and 1727). % XCVH and XCVm. 



I 4 



