390 Annals of the Carnegie Museum. 



study was made of the formations occupying the deeper waters of the 

 coves, but from a couple of tours in a rowboat and from such studies 

 as could be made from shore it was seen that the Chara formation is 

 present in the deeper waters, extending beyond the Potamogeton for- 

 mation, and that the Potamogeton formation is by far the most impor- 

 tant one in the cove. Its structure is typically as follows : 



Fades. — 



Potamogeton natans, Potamogeton heterophyllus. 



Principal Species. — 



Utricularia vulgaris. 



Secondary Species. — 



Naias flexilis, Philotria canadensis, 



Vallisnena spiralis, Potamogeton foliosus, 



Potamogeton lonchites, Potamogeton foliosus niagarensis , 

 Potamogeton zizii, Potamogeton liicens, 



Potamogeton pectinatus, Bidens heckii, 

 Myriophylliim spicatum, Utricularia intermedia. 



The genus Potamogeton comprises the main bulk of the vegetation 

 visible at the surface of the water, although Naias and Philotria are 

 quite abundant below the surface. In the quieter and more sheltered 

 coves the Utricularia vulgaris aspect is quite pronounced during July 

 and August, the society disappearing largely by the time the Potamo- 

 getons have attained their best development. The exact status of the 

 various species of Potamogeton in the structure of the formation j^roved 

 to be an extremely difficult problem, but it is believed that the above 

 classification is as exact as can be made, without establishing quadrats 

 and laboriously determining the structure plant by plant — a very 

 difficult thing to accomplish in such a habitat. 



The Castalia-JVymphcea Formation. 



The Castalia- Nymph cea formation is not so well developed in the 

 coves as one would be led to suspect from the general characters of 

 the habitat — in fact the suspicion at once arises that abnormal condi- 

 tions may have been brought about by the continual search for flowers 

 on the part of the people of Erie, just across the bay. In the more 

 inaccessible ponds of the peninsula the formation appears to be more 

 nearly normal. The formation, as it appears where best developed 

 in a cove to the southwest of the Chimney Ponds, presents the follow- 

 ing structure: 



