544 PHILOSOPHICAL TRANSACTIONS. [aNNO 1754. 



And he further submits, whether this concamerated shell, or body, of which 

 the belemnites is only the habitation, does not appear a strong voucher for this 

 new hypothesis, by more immediately leading us into the connexion and manner 

 of generation (perhaps particular to the testaceous tribe) by remaining within its 

 nidus all its life ; whereas they generally quit them as soon as they are able to 

 shift for themselves. 



The polype is an animal of the vermicular kind ; the bodies of some are long 

 and slender, like a fine sinew or fibre, extremely tender ; and from the head 

 proceeds a variety of claws, or arms, with which it catches its food, and prepares 

 its habitation or chrysalis. They are without doubt of various shapes and tex- 

 tures, according, as he supposes, to the species of the animal that is hereafter to 

 proceed from them ; and very wonderful it is, how so small, so delicate an ani- 

 mal, should be capable of forming so large a body as the belemnites ! but is not 

 every particular performance of nature equally the same to a diligent inquirer ? 

 Some animals in the terrestrial part of the creation, naturally associate and herd 

 together. Others again seek solitude. The same dispositions we find impressed 

 on those of the aquatic system : then why not among the polypi ? as is evidently 

 seen by the prodigious variety of coral bodies, where it seems in some as if thou- 

 sands acted in concert together; in others, where each acts for itself; of which 

 latter is the belemnites. 



The shape of the belemnites is generally more or less conical, terminating in 

 a point, and of various colours, according to the juices of the stratum in which 

 it lay : it has usually a seam or fissure, running down the whole length of it, 

 sometimes filled with a cretaceous substance. In some it is in the middle or axis 

 of the body ; in others on one side. Its interior constitution seems composed of 

 several conoid cortices, or crusts, which, when broken transversely, appear to 

 proceed in striae or rays from the seam or centre ; which seam he takes to have 

 been the habitation or cell of the animal in its polype state, and in which the 

 body was affixed ; or perhaps serving as a syphunculus, in which was a ligament 

 that proceeded from the nucleus in its perfect state. 



The crusts it is composed of probably denote certain periods in the age of the 

 animal; as the annual rings in a piece of timber, its age: but what those periods 

 are, we are not acquainted with ; see fig. 11, 12, 13, 15. The animals of the 

 testaceous tribe in general, as they increase in age, increase their shell in thickness 

 till they have lived their stated time, or attained to good old age ; and that is 

 done by adding a new crust or lamina to it, as several, if not all the tubuli, the 

 oysters, and the nautili, witness ; after which they become inactive and dull, the 

 effect of extreme old age, suffering other marine bodies, as worms, oysters, &c. 

 to penetrate and affix themselves to their outer coat. The like appearances we 



