206 PHILOSOPHICAL TKANSACTIONS. [aNNO 1751. 



though in common they are the habitations of animals, each species vaiying in 

 form and bulk, and composing its cell in various forms and manners, and of 

 different consistences, constitutes their essential character. As oysters, scallops, 

 muscles, cockles, snails, &c. have a power given them, by the Author of Nature, 

 of forming and enlarging their separate dwellings ; to these bodies, the subjects 

 of this treatise, the same power is given, but in large families. In the madre- 

 pora, its animal occupies the extremity ; in the millepora, the substance ; in 

 corallines and sponges, the void places ; in coral and lithophytes, the cortical 

 parts. Each of these animals, according to their kind, furnish substances dif- 

 fering as much in consistence as in form. That of coral is extremely hard, and 

 compact ; the madrepora and millepora are of a stony, but more loose texture ; 

 the coralline is still more soft ; the lithophyton, of a substance nearer horn than 

 stone ; and the sponge is soft and elastic. 



We observe a great variety in the operations of nature : the crab, the cuttle- 

 fish, and the sea-spider, are endowed with a testaceous covering ; the esculent 

 sea polype, and others of that class, have no such defence. So most of the 

 animals hitherto noticed in this treatise, have a secure retreat ; but there is a 

 production denominated, by Imperatus, lorica-marina, which has no such con- 

 venience. It is as it were a soft madrepora. It grows at the bottom of the sea, 

 and is a series of circular tubes, of about half an inch long, and 2 or 3 lines in 

 diameter. Each of these, at the end most remote from the centre, is furnished 

 with a sphincter, from which are occasionally protruded the legs or claws of the 

 animal, like those before mentioned. The tubes themselves are likewise at 

 pleasure lengthened and shortened. They are fastened to the rocks by a com- 

 mon broad surface, after the manner of coral and such like marine productions, 

 and are of a coriaceous substance. Hither likewise may be referred the soft 

 lithophyton, usually called the sea-mulberry, and described by our author, which, 

 on observation, exhibits nearly the same phenomena as the preceding. 



As to our author's opinion concerning the propagation of these animals : he 

 supposes that they spawn as oysters do ; and that their spawn is inveloped in a 

 viscous substance, like that of testaceous and other fish ; and that by this visco- 

 sity it is fastened indifferently to whatever solid body lies in its way, whether it 

 be a rock, glass, broken pots, flint-stones, &c. This viscous matter, coming 

 to stagnate, is changed, according to its nature, into a solid and forms a lamina 

 or stratum, such as is observed at the base of these productions, and ser\-es as it 

 were for their first principle. The egg, inveloped in this viscous substance, is 

 hatched in its proper time, and furnishes the animal, which resembles the sea- 

 polype and other soft fish. These animals have all the necessary organs, and 

 among others a particular gut, which, in the cuttle-fish, is filled with a black 

 liquoif the use of which, according to the vulgar opinion, is that of being poured 



