On the Sexual Characters of the Family of Naiades. 117 



the abdomen, the connecting integument was found to be hollow, 

 and nothing resisted a flexible probe in passing through from one to 

 the other. This operation was performed with great care, with the 

 tender and soft end of a spear of grass drawn from a green plant. 

 But there was no appearance of the entrails of one, having come in 

 contact with those of the other, for the integument was less than one 

 tenth of an inch in its whole thickness, and in length from the body 

 or trunk, of one fish to the other, it was three tenths, and in the 

 water, when the largest fish was in its natural position, the small one 

 could, by the length and pliancy of this skin, swim in nearly the same 

 position. It was not ascertained whether, they were of different sex- 

 es, or of the same* 



When these fish came into existence it is probable they were of 

 almost equal size and strength, but one " born to better fortune," 

 or exercising more ingenuity and industry, than the other, gained a 

 trifling ascendency, which he improved to increase the disparity, and 

 by pushing his extended mouth in advance of the other, seized the 

 choicest and most of the food for himself. Yet though he probably ha- 

 ted the incumbrance of his companion, and wished the " marriage 

 tie cut asunder," he afforded protection to his " weaker half," and 

 could not eat it without swallowing himself. 



Fort Johnston, N. C, Dec, 7, 1833. 



Art. XXI. — Observations on the Sexual Characters of the Ani- 

 mals belonging to Lamarck's family of Naiades ; by Jared P. 



KlRTLAND, M. D. 



This interesting family, has of late, received an accession to its 

 attractions, as well as numbers, by the discovery of many undescri- 

 bed species, in different parts of the world, particularly in the rivers 

 and lakes of the United States. 



In consequence of the characters, which are employed for scien- 

 tific arrangement, in the systems of conchology, being derived, ex- 

 clusively from the shells, the animals seem in a measure, to have 

 been disregarded. Their general anatomical structure is not well 

 understood : much less the intricate, and minute conformation of their 

 sexual organs. It is a disputed point, whether, they are androgy- 

 * nous, or whether, they possess distinct sexes. 



Mr. Say, in the second No. of the American Conchology, under the 

 article Anodonta, remarks, that " the principal naturalists and anato- 



* 



