STUDIES IN MARINE ECOLOGY. 223 



C. Animals Found in Brief Examination on Surface of Substratum. 

 Crustacea : 



Cancer irroratus, 



Libinia dubia carrying the sponge, Cliona celata, (?) 



Pagurus longicarpus carrying the hydroid, Hydractinia echinata, 



Panopeus sayi. 

 Gasteropoda : 



Littorina litorea, very numerous. 



D. Animals Found in Sampling the Substratum. {Three spadesful were dug.) 



Platyhelminthes: • Annelida: 



Linens ochraus. Clymenella torquata, 



Leprcea rubra, 



Mollusca: Lumbrinereis tenuis, 



Cumingia tellinoides. Nereis limbata, 



Nassa trivitatta. Pectinaria gouldii. 



Water analyses for this association are shown in Table VII. 

 The table includes the last six items from the preceding table, 

 since the conditions described in those collections are as char- 

 acteristic of the one as of the other. A discussion of the water 

 analyses for this and the other associations of the eroding shore 

 series is reserved to a later section. 



Here this series logically ends so long as the shores remain 

 under erosion with a gradual wearing away of the land to expose 

 more rocks, which would result in the association of the exposed 

 rocks moving gradually forward as erosion proceeds. In case 

 the shore line should remain stationary for sufficient time, the 

 rocks might be worn away to sand and this association might 

 conceivably pass gradually into that of the sand bar which will 

 be considered in the next section. On the other hand if the 

 configuration of the land changes so that currents no longer 

 cause erosion, but deposition sets in, then in the region of the 

 present rock associations one may find sand deposited and the 

 sand bar association might be reached by that route. If the 

 region becomes still more quiet, mud might be deposited and 

 the rock association would then pass to the My a association and 

 with further deposition, pass into the Uca or Melampus stage. 

 The physical factors correlated with these associations will be 

 given on a later page and anyone interested in completing this 

 series on either of these possibilities, can readily do so. 



