592 PHILOSOPHICAL TRANSACTIONS. [aNNO I76I. 



These joints are generally about -yV of an inch in length, and the same in dia- 

 meter, except a few near their insertion in the stem, which are shorter and 

 thicker the nearer they are to it. We may plainly trace a small hole here 

 through the midst of the joints, which communicates through the centre of the 

 starry vertebrae in the main stem, to the hooked joint at the extremities of 

 these arms. 



On the under or inner side of those joints, that are near the end of the arms, 

 we may discover 4 minute tubercles in every joint, 2 at each end; these are of 

 the same testaceous substance with the rest of the joint. By means of this un- 

 even surface, together with the hook, which the last joint forms, bending down- 

 wards, the animal can take a more secure hold of whatever it seizes. But as 

 the stem of this animal appears evidently to be broken off short at the bottom, 

 we must remain in doubt, whether it moves about in the sea, or is fixed to rocks 

 and shells by a base, like corals, sponges, and keratophytons, till some future 

 discovery shall clear up this matter more to our satisfaction. 



In examining the main stem or column, we may observe some single joints or 

 vertebrae projecting a little farther than the rest. There are generally 3 or 4 of 

 these in each division, between the whirls of arms; the angular parts of these 

 joints end in small round knobs; but the knobs at the corners of the vertebra, 

 immediately under the head of the animal, are remarkably larger than the rest. 

 The joints or vertebrae of the stem vary in thickness, as well as in diameter; 

 the common thickness is about -^ of an inch, but in the last 4 divisions ap- 

 proaching towards the head, they gradually diminish, till they become extremely 



thin. 



We now come to what is called the head, perhaps the body of the animal: 

 for in the centre of this dry specimen, there still remains a cup of a crustaceous 

 substance, and of an oval form, about an inch in length, three quarters of an 

 inch over, and a quarter of an inch deep; in the centre of this, as was observed 

 before, is a small hole, which apparently communicates with the internal part of 

 the vertebrae of the stem : in this cup or cavity it is probable were the intestines 

 and stomach of the animal, as in the asteria, called caput medusae. This cup 

 is supported by the bases of 6 dichotomous testaceous arms, or branches, per- 

 haps 5 is the natural number, for one seems irregularly placed. These lower 

 parts, or bases of the branching arms, consist of 3 joints each, and surround 

 the cup, to which they seem united: each of these divide into 2 other jointed 

 branches, that are round or convex on their under side, but flattish on tiie up- 

 per, with a deep groove running along the middle, which is furnished with 2 

 rows of suckers, as in the sepiae and iisteriae. From the upper edges of each alter- 

 nate joint of these branches, arise 2 rows of small jointed claws, like fingers; 

 these 2 opposite rows bend in towards each other : each small branch, or finger. 



