262 



student of botany and physiography. Under the caption " the 

 physiographic origin of Presque Isle " Jennings describes the 

 changes which have been produced in the conformation of the 

 shore and hills by the slow action of the currents and waves of 

 Lake Erie. He shows by a series of figures and in his descrip- 

 tion how the evolution of the island has taken place, the United 

 States hydrographic charts made at various intervals in the past 

 affording important data upon which to base a survey. The 

 author shows how the development of the climax vegetation has 

 been influenced by the physiographic changes that have taken 

 place in the island. Under the heading " ecological structure and 

 pevelopment of the vegetation " is presented a detailed account 

 of the plant formations, and finally, a list of the 420 species, 18 

 varieties, and i hybrid collected at various times on Presque Isle. 

 The reviewer believes that Jennings has subdivided the natural 

 vegetation into too many formations. For example, the Lagoon- 

 Marsh-Thicket-Forest Succession has been subdivided into the 

 Populus-Salix Formation, the Potamogeton Formation, the Typha- 

 Scirpus Formation, the Sabbatia-Linum Formation, etc. The 

 treatment would have been much simplified if all of these forma- 

 tions (which are not formations as the reviewer understands 

 them) had been grouped under one, viz., "the lake formation", 

 and if the smaller areas of vegetation had been termed asso- 

 ciations, or circumareas. Then, instead of describing the vege- 

 tation of each lagoon, separately and categorically, much space 

 might have been saved and condensation made possible by 

 referring to the lagoon where such and such a type of vegetation 

 occurred naturally. These remarks are not made in a fault- 

 finding spirit, but merely to suggest points where forthcoming 

 papers of a similar character might be improved without impair- 

 ing the scientific value of the work. 



John W. Harshberger 



