44 LINN^AN GENERA. 



In other oysters, animalcules of the same kind were found not con- 

 joined, but swimming by one another, where they seemed in a more 

 perfect state, and were judged by Leeuwenhoek to be the animalcules 

 in the roe or melt of the oyster. 



A female oyster being opened, incredible numbers of small oysters 

 were seen, covered with little shells, perfectly transparent, and svAim- 

 ming along slowly in the liquor ; and in another female, the young 

 ones were found of a brown coloui', and without any appearance of life 

 or motion. 



In the month of August oysters are supposed to breed, because young 

 ones are then found in them. Leeuwenhoek, on the 4th of August, 

 opened an oyster, and took out of it a prodigious number of minute 

 oysters, all alive, and smmming nimbly about in the liquor, by means 

 of certain exceeding small organs extending a little way beyond their 

 shells ; and these he calls their beards. In these little oysters he could 

 discover the joinings of the shells ; and perceived that there were some 

 dead ones, with their shells gaping. These, though so extremely 

 minute, are seen to be as like the large oyster, as one egg is like 

 another. 



As to their size, he computes, that 120 of them in a row would extend 

 an inch ; and consequently, that a globular body, whose diameter is an 

 inch, would, if they were also round, be equal to 1,728,000 of them. lie 

 reckons 3,000 or 4,000 are in one oyster, and found many of the embryo 

 oysters among the brairds ; some fastened thereto by slender filaments, 

 and others lying loose ; he likewise found animalcules in the liquor 500 

 times less than the embryo oysters. 



Genus 15.— ANOMIA. 



Animal an emarginate ciliate strap-shaped body, with 

 bristles or fringes affixed to the upper valve ; arms two, 

 linear, longer than the body, connivent, projecting, alternate 

 on the valve and ciliate on each side, the fringe affixed to 

 each valve ; shell bivalve, inequi valve, one of the valves 

 flattish, the other gibbous at the base with a produced beak, 

 generally curved over the hinge ; one of the valves often 

 perforated near the base ; hinge with a linear prominent 

 cicatrix, and a lateral tooth placed within, but in the flat 

 valve on the very margin ; two bony rays for the base of the 

 animal. Plate VII. fig. 15. 



Anomia undulata. — The Waved Anomia. Plate VII. 

 fig, 15. Suborbicular, with fine irregular, undulated, longi- 

 tudinal, smooth strioe, crossing transverse curved ones ; in- 



