154 The Ottawa Naturalist. [March 



physical features. Thus the frog, salamander arid turtle which dom- 

 inate the animal life of the marshes give way entirely to other types 

 on the uplands. 



The influence of this familiar and powerful factor, the character 

 of the soil or rock, in determining the major features of land biotas, is 

 paralleled by the control which the physical character of the bottom 

 exercises over marine biotas. When marine dredging is conducted with 

 the object of ascertaining the relationship of the various kinds of 

 bottom to the kinds of life living on them, as most of the writer's have 

 been, the association of certain faunal with certain bottom facies be- 

 comes clearly apparent. The control exercised by the physical character 

 of the bottom in bringing together certain groups of animals and plants 

 into marine communities and in excluding others is just as effective 

 as is the operation of the physical character of the land surface in 

 producing varied faunal and floral groups. 



The distribution of the sponges is one of the interesting features 

 brought out in collecting the fauna listed above. These were found in 

 such abundance on the coarse rocky bottom at the mouth of the Avon 

 river and on the hard muddy sand bottom off Kingsport as to complete- 

 ly fill the dredge in some hauls. On soft mud bottom however, not a 

 single sponge was taken. The molluscoidea also show a strong affinity 

 for hard bottom, five species being taken on gravel and rocky bottom, 

 one on firm muddy sand bottom, and not a single species on soft bottom. 

 The four species of echinoderms taken were all found either on gravel 

 or -the comparatively firm sandy mud bottom. The preference of the 

 Crustacea for hard or firm bottom is also evident. The seven species 

 listed were all taken either on gravel, rocky, or sandy mud bottom, and 

 but two of them on soft bottom Only two specimens of P. acadianus 

 were taken on soft mud bottom and 39 specimens were taken on the 

 sandy mud bottom. 



The fauna of the soft mud bottom shown by the list includes 

 thirteen species which are confined to the four groups, vermes, pelecy- 

 pods, and gasteropods and Crustacea. Two of the species were not 

 found outside the limits of the soft mud. The specialized character 

 of the black mud fauna is apparent from the fact that it contains no 

 representatives of the Porifera, Molluscoidea nor Echinodermata The 

 mud bottom in developing its soft bottom facies draws from but four 

 of the eight phyla which are abundantly represented in the region. 



When you are in or near the forest this summer, never leave your 

 camp fire until it is absolutely OUT. Never throw away lighted 

 matches or tobacco or pipe ashes. These rules are followed by all 

 veteran sportsmen and good citizens. 



