Ortmann; Families and Genera 01 Najades. 



313 



from Portsmouth had eggs only, and thus the beginning of t lie breeding 

 season is shown to lie in autumn. 



The soft parts have been described and figured by Lea (Obs., I, 

 1834, pi. 5, figs. 6 and 7: and Obs., X, 1863, p. 433), but the figure is 

 very poor. 88 



-,sa 



an 



'\ br 



mp 



Fig. 17. Cy progenia irrorata (Lea). 

 Gravid female, from Ohio River, Ports- 

 mouth, Scioto Co., O. (Cam. Mus., No. 

 61, 4,763-) 



Branchial, anal, and supra- 

 anal as usual, the latter two 

 separated by a very short 

 mantle-connection. Branch- 

 ial with papillae, anal finely 

 crenulated. In front of the 

 branchial, the inner edge of 

 the mantle has a series of fine 

 crenulations which soon di. - 

 appear, this edge becoming 

 smooth. Palpi normal, pos- 

 terior margins connected at 

 base only. 



Gills short and broad, the 

 inner much wider than the 



outer throughout its whole length. Diaphragm normal, inner lamina 

 of inner gills free from abdominal sac, except at the anterior end. 

 Anterior attachment of gills as usual. 



Septa and water-tubes in both gills normally developed, the latter 

 moderately wide in the male and the non-marsupial gills of the female. 

 Marsupium formed by a section in the middle of the outer gill; in 

 fact this section is a little more toward the anterior end of the gill. 

 Ovisacs few (three to eight in my specimens; up to eleven reported 

 by other authors; Simpson gives for the genus twenty-three as maxi- 

 mum), hardly different in width from the rest of the water-tubes, 

 that is to say in the longitudinal direction. But, when charged, they 

 swell somewhat in the transverse direction, so as to become subcylin- 

 drical. The ovisacs project to an extreme degree beyond the edge of the 

 gill. Although they begin near the base of the gill, and although a 

 considerable part is enclosed between the original laminae of the gill, 



38 Lea's figures are quite characteristic of the marsupium itself, but the position 

 of the latter in the animal (fig. 7) is wrong. Apparently the anterior and posterior 

 ends of the body are inter-changed. The marsupium does not coil forward, as this. 

 figure shows, but backward. 





