PLATE IV— Coutinued. 

 SCHIZAMBON (?) FISSUS, Kutorgil. 



Fig. SI. A pedicle-valve ; showing the external character of the aperture. After Kutoroa, op. cit., pi. 

 vii. dg. 5a'). X 2.5. 



ScHiZAMBON (?) FLSSt;.-;, var. Canadensi.s, Ami. 



Fig-. 32. A brachial valve from which the shell is luirtially broken ; showing- the impression of an internal 

 median septum. All the spines have been removed except those at and near the niarg-ins. 

 These have been pressed tog-ether in one plane, giving- them the appearance of lieing more 

 closely set than when standing- at their normal angle upon the surface. X 2. 



Fig. 33. The pedicle-valve ; showing the external character of the pedicle-passage. X 2. 



Fig. 34. A jiedicle-valve fi-om which most of the shell has been broken, giving a cross-seittion of the 



sipho near its imiei' extremity. X 2. 

 Fig. 33. A brachial valve, the con-elate of fig. 34. The surface retains most of the shell, but the sjunes 



are lirokeu, .showing only their bases, except at the mai-gins wliere a portion of their length is 



retained. X 2. 



Fig, 30. A jiedicIe-valve, so broken as to show the inner edge of the sipho. 



All the above specimens are from the horizon of the Utica slate. iVear Gloucester, 

 Ontario. 



SiPHONOTRETA (?) MiNNESOTENSIS, Sp. IIOV. 



Fig. 37. View from the brachial side of a sjiecimen retaining- the valves in juxtaposition and preserving 

 most of the epidermal layer of the shell. The spine-bases about the beak are noticeably large 

 and more closely set than over the i-est of the surface, where they occur at considerable dis- 

 tances along the concentric varices. The entire length of the spines is evidently not repre- 

 sented in the fringe about the margin. X 2. 



Fig. 38. The opposite valve of the same specimen. The imperfection of the valve in the umbonal region 

 has ren<lered it impossible tc5 determine with accuracy the genei-i<- character of the species. X 2. 

 Trenton Limestone. Minneapolis, Minnesota. 



