THE NAUTILUS. 143 



larger in larger specimens. Ovisacs as distinct as in other 

 forms; their number may go up to 20 and even more. The 

 marsupiuin assumes, when larger, the normal, kidney-like 

 shape, but there is always a considerable part of the gill, at the 

 posterior end, non-marsupial. 



Inner edge of mantle, in front of the branchial, with very 

 variable papillae. My former description apparently represents 

 not the normal condition, for in the present material the papillae 

 are posteriorly (near the branchial) generally very indistinct, 

 often absent, and only anteriorly there are one, two or three 

 rather long ones, of subcylindrical shape (but hardly "hair- 

 like"). 



Glochidia as described before, almost subspatulate (with 

 anterior and posterior margins nearly straight and forming an 

 indistinct angle with the lower margin). They are much 

 higher than long. Length 0.28, height 0.27 mm. (former 

 measurements 0.22 x 0.28). 



I have seen in none of the specimens from the Holston and 

 Clinch Rivers a trace of the byssus of the adult shell. 



Color of soft parts: whole mantle, and also the gills and pos- 

 terior part of abdominal sac, suffused with black. Mantle 

 margin intensely black posteriorly. The charged marsupium 

 is white, without pigment on the edge, and contrasts strongly 

 with blackish color of the rest of the gills. 



I think Medionidus is a good genus, distinguished by char- 

 acter of shell and soft parts. The location of the marsupium, 

 and of the marsupial swelling of the female shell is different 

 from that of the allied genera (chieliy Eurynia), but also shell 

 sculpture and papillae of mantle offer good characters. 



( To be concluded. ) 



NOTES. 



GONIDEA ANGULATA Lea. In a letter from Mr. John A. Allen 

 who has been collecting shells in Oregon, especially about his 

 home in Oswego, he states, that Gonidea angulata Lea was in 

 great abundance in the canal which connects Tualatin River 

 with Oswego Lake, Clackamas Co., Oregon. Only a few young 

 ones were seen. The Gonidea were well sunk in the gravel, 



