VOL. XLV.] PHILOSOPHICAL TRANSACTIONS. 471 



one place, of which he has no knowledge. He has made inquiries about these 

 imagined changes, of people of many nations, but could never learn any thing 

 to the purpose. He has seen the fish itself in several countries, and found they 

 spawned like other fishes, and grew in size, without the least similitude to what 

 has been asserted. He adds further, that these fishes delight in very clear water, 

 in rivers with stony or sandy bottoms, and are never found in standing lakes, or 

 rivers passing through marshy or mossy grounds, where frogs chuse most to be. 



As to inquiries concerning the crabs' eyes, he expresses a surprise to find natu- 

 ralists differ so much from each other, and yet not one of them he has ever seen 

 giving any true account of the situation, formation, and casting of these con- 

 creted bodies. He therefore is so obliging to send the following description 

 from his own observation and knowledge. Those concretions called crabs'-eyes, 

 are found, he says, in the bodies of craw-fish. Each fish annually produces two, 

 one on either side of the anterior and inferior part of the stomach, and each is 

 generated about a point lying between the coats of it. The flat or concave side 

 lies next the internal coat, which is very thin and clear, though strong and homy ; 

 the convex side is consequently outwards, and is immediately covered by the fleshy 

 and softer coats of the stomach, whose fibres make impressions on its surface. 

 Between these two membranes it grows by degrees lamellatim, and is supplied 

 with petrifying juices discharged through the mouths of vessels or sudamina 

 opening on the internal surface of the outer coat. The inner membrane, being 

 horny, gives resistance only; hence the stones are concave on that side, and the 

 first remarkable scale, on which all the others are formed, may be perceived in 

 the centre, the brims or circumferences of many of the rest being very apparent. 

 At the time when these stones are not to be found in the animal, there are little 

 circular spots, somewhat opaque, and whiter than the rest of the stomach, to be 

 perceived in their place; nearly opposite to which are tenacious mucilaginous 

 substances, formed like little placentulse, and called by some the glands of the 

 brain; these are larger, and more perceptible, when the stones are wanting; but 

 are not turned into stones by different degrees of induration, as some have ima- 

 gined them to be. 



It is believed, he says, that they cast these stones with their shells, which they 

 shed every spring, but he finds this is not the way of getting rid of them, for, a 

 little before, or after the time of their casting their shell, the stones break through 

 the internal or horny coat of the stomach, and being ground or broken by the 

 three serrated teeth in it, become dissolved in the space of a few days, which 

 makes it difficult to find them just at this time, and so gives ground to imagine 

 they are cast with the shells. He says however, he has found several of them 

 in the stomach partly consumed; and a further proof that they are so consumed 

 is, he thinks, their being never discovered in rivers, though the fish themselves 



