VOL. XIX.] PHILOSOPHICAL TRANSACTIONS. 135 



and besides these parts serving for nutrition, I could not distinguish any other 

 viscera. 



But that it had no brain, heart, gills, liver, or parts for generation, or 

 something analogous to these, I dare not affirm ; yet this is certain, that nature 

 has carefully supplied some imperfect animals, such as the leech, a water reptile 

 as this, with large and conspicuous organs for nutrition, while other principal 

 parts, if they have any, are hardly, if at all, to be distinguished. 



But what was most remarkable in its inward structure, was the curious con- 

 trivance of the muscular parts, for the performance of its several motions; 

 these were very apparent, being both large and distinct : one long continued 

 stripe of red fleshy fibres, about the 6th part of an inch broad, ran directly 

 along the middle of the back, from the head down to the tail : this fleshy stripe 

 sent out from each side, like so many rays, 36 several ;pair of smaller lateral 

 muscles, which, by the considerable interstice between, I could easily distin- 

 guish from each other, making so regular a figure altogether, that they might 

 very aptly be resembled to the spine, or back bone of the passer marinus, or 

 common plaice fish, when it is entire with all its ribs or transverse processes, 

 issuing by pairs from both sides of each vertebra, from the head down to the 

 tail : in this manner every particular foot and fin were supplied with their 

 correspondent muscles, to give them motion, either together or apart, as the 

 necessity or design of the animal required. And besides, considering this sort 

 of muscular mechanism, with the taper shape of the body, and the position 

 and use of the many prickles interspersed among the hairy shag that covered 

 the sides ; it seems very evident to me, that, besides its progressive motion, it 

 had also the power (as have most of the many footed land-reptiles, and some 

 water insects I have observed) of contracting its body in such a manner, that 

 bending its head inward, it rolled the rest of the body round it as a centre, 

 making a figure like a rope coiled into a helix, and in this posture guarded 

 itself from violences that might annoy it. So we may often see the large hairy 

 caterpillars, that have not a little resemblance to this creature, when molested 

 by any offensive object, straight secure themselves from the violence, by gather- 

 ing up their body in this manner, and making their hairy bristles start out 

 directly forward. 



An Explanation of the Figures, drawn half the Size of Life. 



Fig. 6, pi. 3, aaaaa the downy list running along the back ; bb the two tri- 

 angular scales that cover the anus; cccccccc the verge of fine changeable green 



