: 



NAIADS 



NAIAD. r. 



H I 



AnodmtaJhKiatila. 



In plate xx. (Mr. Garnet's paper on the ' LunclUbronchUtc Conchifcra') 

 will tic found a figure of the animal from the orurlum of an Anodonla, a> teen 

 in the Held of the microscope ( j-inch focui) ; and In plate xviii. the deposition 

 of the heart, pericardium, excretory orpins, &c. of Anodonta onalina is nhown. 



Anodonta undulala, apparently ready to spawn. 



a in the cut represents a sac with its ova ; 4 represents the ovum with 

 its perfect young shell included ; c represents the honeycomb appear- 

 ance, and is eight times magnified. 



Two female* of I'nin radiatui as they were nocn with the parts protruded n< 

 ey lay at the bottom of a baain of water. Dr. Lea states that these female* 

 it on two quite different form* aa regards the inferior portion of the mantle, 



they lay 

 put on t 

 u exhibited abore. 



Dr. Lea (vol. i.) state* that it seem* to be a matter of doubt on 

 what these animal* subsist He says that he has strong reasons for 

 believing that they feed on animalcules which are ever found to exiot 

 in water, and which they might separate from the constant stream 

 which they pass from the posterior part of the shell, and which munt 

 be taken in at another part This operation he witnessed frequently 



in a Teasel in which he kept the A'uiW-r for some months. If the 

 water was not changed for twenty-four hours he uniformly found the 

 animals quiet, but within a few minutes after it was changed they a* 

 uniformly commenced the passage of this constant stream. He adds 

 that ho cannot suppose this operation to be for the mile purpose of 

 breathing, as there is no intermission in the stream of water, and 

 the quantity thrown out is too great for this purpose only. He believes 

 it to be the result of the action of the separation of the animalcules 

 from the water. 



In the Museum of the Royal College of Surgeons in London several 

 preparations of the internal organs of the fresh-water muscle, Anoilvn 

 cyynciu, will be found. 



The brilliant and variously-coloured nacre with which many of the 

 species are lined and the extreme thickness of some of the shells are 

 very remarkable. That pearls should be found in them will not sur- 

 prise those whoso attention has been drawn to their internal surface. 

 Pennant remarks that Mya margaritifera of Linnaeus ( Ifnio tlongattu) 

 is noted for producing quantities of pearls, and formerly there were 

 regular fisheries in many of our rivers to obtain them. As many aa 

 sixteen have been taken from one shell The Esk and the Conway 

 were famous in this way. The latter river in the days of Camden was 

 noted for them. Sir Richard Wynn of Gwydir, chamberlain to 

 Catherine, queen to Charles IL, is said to have presented her majesty 

 with a Conway pearl which is to this <lny "honoured with a place in 

 the regal crown. Pennant, who states this, adds, that the shells are 

 called by the Welsh Crigen Diluw, or Deluge Shells, as if left there 

 by the Deluge. The river Irt in Cumberland also produced them ; 

 and Sir John Hawkins, the circumnavigator, had a patent for fishing 

 that river. Britain indeed had early acquired a reputation for it* 

 pearls; for, according to Suetonius, they were Caesar's inducement 

 for undertaking hia Irtish expedition. (' Jul. Ca'-ar,' o. 47.) This 

 however does not seem very probable. Pliny (ix. 35) indeed speaks of 

 the pearls of our island as small and ill-coloured, and refers to the 

 breast-plate which Ccesar himself had brought home and dedicated to 

 Venus Oenetrix in her temple, adding that he wished it to bo under- 

 stood that the offering was formed of British pearls. 



Ireland has produced pearls of considerable size and some value, 

 especially in the rivers of Tyrone and Donegal. One wi ighod 3(> caratx, 

 and was valued at 402., but it was foul, and so lost much of its wurtli. 

 Other single pearls were sold for 41. 1 0., and for as much as lOi, Tin 

 hist was sold a second time to Lady Glenlealy, who put it into a neck- 

 lace, and refused SOI. for it from the Duchess of Ormoud. Pennant, 

 who quotes from the abridgment of the ' Phil. Trans.,' speaks of the 

 last century as the time when these large Irish pearls were procnn-il. 

 We have seen some lately of considerable size, fair shape, and pretty 

 good colour. 



Dr. Lea, in his final arrangement, admits only-two genera, Margarita 

 and Platirii. The first of these has been preoccupied by Lench tn 

 designate a genus of Marine Conchifers. [MAHUAKITA.] We shall 

 however retain the name in this article, in order to present to the 

 reader the leading features of Dr. Lea's arrangement and the form* 

 of the sheik. 



Margarita. (Lea). 



1. Sub-Genus. I'nio. Having a Cardinal and Lateral Tooth. 



Ex. Unio alaliit. 



Symphynot*. 



t'nw nlntwi, 



a, part of the wing of the valve broken off, showing the M-mphvnote character 

 reduced. 



