98 The Ohio Naturalist. [Vol. XIII, No. 5, 



curved lateral surface. Their openings are in the shape of mouths 

 having their borders fringed with stiff, tapering bristles. The 

 under lip of the mouth is very thick and has a cushion extending 

 into the interior of the bladder. The upper lip is very thin and 

 from it a transparent valve comes down to meet the inner edge of 

 the cushion, thus closing the opening. By pressing against this 

 valve minute plants or animals are able to enter the bladder from 

 which it is impossible for them to escape, because of the valve. 



Silphium perfoliatum, Indian-cup, has its leaves arranged 

 opposite each other on the stem, and united to form a cup. This 

 cup is filled with water, probably partly rain and partly some 

 excretion from the plant itself. 



Dipsacus sylvestris is a coarse herb having its leaves arranged 

 opposite each other, forming a cup to catch water, much like the 

 Silphium. Their edges and mid-ribs are covered with prickles. 



In the second group are : 



Drosera rotundifolia L. 

 Drosera intermedia Hayne. 



The different forms of Drosera, Sun-dew, are usually rooted in 

 damp, mossy soil or bogs. The way in which these plants catch 

 their prey is by means of fine red filaments which are clavate on 

 the free ends and tipped b}^ a drop of fluid. These filaments 

 stand out from the upper surface of the leaf, the under side being 

 smooth and without hairs. They are of unequal length, the 

 longer ones being near the outer edge, the shorter ones in the center. 

 There are on one leaf, sometimes as many as two hundred of these 

 tentacles. The clavate head is really a gland which secrete a 

 thick, sticky, sweet fluid. It is remarkable that in making 

 experiments, by placing bits of non -nitrogenous substances upon 

 the leaf, the movement is scarcely perceptable, in response, while 

 when insects alight upon the surface, the process immediately 

 begins. In many instances the leaf itself becomes concave, so 

 that when the tentacles are down, it has the appearance of a 

 closely doubled fist. When the insect alights near the center of 

 the leaf it is covered by the secretion of all the tentacles. 



Those in the third group are : 



Silcne antirrhina L. 



vSilcne antirrhina divaricata Rob. 



Silene virginica L. 



Silenc noctiflora L. 



Silene rcgia Sims. 



vSilene armeria L. 



Silene conica L. 



Silene caroliniana Walt. 



Tricuspis seslerioides (Mx.) Torr. 



Carduus nniticus (Mx.) Pers. 



Carduus odoratus (Muhl.) Port. 



Parsonsia petiolata (S.) Rusby. 



Polanisia gravcolcns L. 



Circaea alpina L. 



