RESEARCHES IN HELMINTHOLOGV AND PARASITOLOOY. 169 



[February, 1883 No. 509. See Bibliography.] 



On the Rcproductiaii ami Parasites of Anodonta finviatilis. — Prof. 

 Leidy directed attention to a basketful of living fresh-water mussels, 

 Anodonta ftnviati/is, which were obtained for him through the kind- 

 ness of Rev. Jesse Y. Burke, and are now placed at the disposal of 

 members who wish to have them. They are fine, robust specimens, 

 the larger ones measuring 6 inches in length by 3 inches in height 

 and almost 2^2 inches thick. They were obtained from a little pond 

 occupying an old marl pit near Clarksboro, Gloucester Co., N. J. 



These mussels appear to be e.Kceedingly prolific. The pregnant 

 females have the branchial uteri, as they have been appropriately 

 named by Dr. Isaac Lea, enormoush- distended with perfected em- 

 bryos. These appear with a cinnamon-brown shell, having a con- 

 spicuous spinous tooth or hook to each valve, and are furnished with 

 long byssal threads. Wishing to ascertain the proportionate amount 

 of embryos, the following plan was adopted : In an individual 6 

 inches long the soft parts were weighed and found to be 135.44 

 grammes. The branchial uteri weighed 64 grammes and the inner 

 gills 7.34 grammes. Supposing the latter to be the same weight as 

 the outer gills, free from embryos, this weight subtracted would 

 leave 56.66 grammes as that of the embryos and 78.78 grammes as 

 the weight of the rest of the animal. In another specimen, in which 

 the weight of the soft parts was 1 13.75 grammes, the branchial uteri 

 weighed 45. 5 grammes and the inner gills 5. 2 grammes. Subtracting 

 the weight of these would leave 40.3 grammes as the weight of the 

 embryos and 73.45 grammes for the rest of the animal. In another 

 specimen by weight and counting the embryos in a milligramme 

 were estimated to be 1,280,000. 



The mussels are infested with many water mites creeping about 

 among the gills. The young of the same in various stages were 

 observed imbedded in the mantle. The mite appears to be identical 

 with the species Ata.v vpsi/op/iorus, which is a parasite of the common 

 mussel, Anodonta eygnea, of Europe. It was discovered and de- 

 scribed just 100 years ago, under the name Arams ypsilophorus, by 

 Dr. Christopheri Gottlieb Bonz (Nova Acta Phys. Med. Acad. 

 C. L. C. Nat. Cur., Nuremberg, 1783, 52, Tab. i, figs. 1-4). It is 

 described and figured by Pfeiffer, with the name Limnochayes ano- 

 dontee (Naturg. deutscher land und suss-wasser Molusken, 1821, 

 Taf. I. fig. 12) : by Dr. Karl Ernst v. Baer, under the name of Hy- 

 drachne concharuni (Nova Acta, Bonn, 1826, 590, Taf. xxxix, fig. 

 19) ; by P. J. Van Beneden (Mem. de I'Acad. R. des sciences de 



