110 The Middle Devon j ax Deposits of IMarveaxd 



The writers unpublished work on llie Hamilton ,strati!j,Taj)liy of Vir- 

 ginia indicates that distinct faunal facies existed during Hamilton time 

 in that region that showed even greater contrasts than those which 

 characterize the Portage faunas of eastern and \\estern Xew York. Ex- 

 tended studies liy the writer ol the local ])('cidiarities of various other 

 Devonian faunas have convinced him that the rather sharp contrasts 

 between the Onondaga fauna of Maryland and that of Xew York are in 

 no sense anomalous, but represent regional and bathymetric differences 

 in the same fauna. It is quite as important in Devonian as in TertiaiT 

 formations that stratigraphic paleontologv' should be studied ami inter- 

 preted "by the combined aid of the laws of geographical distribution 

 and of the bathymetric arrangement of marine animals and of sedimentary 

 matter." 



It may be profitable to call attention here to some of the fundamental 

 factors which tend to develop different ty}H's of a fauna in different parts 

 of the same sea at present and which operated in about the same manner 

 in the Paleozoic seas. The surprising influence of local environment in 

 producing great variation in tlie kind, variety, and abitndauce of marine 

 life along different parts of the same coast in our present seas is a fact 

 which paleontologists are prone to overlook. Concerning the scarcity of 

 marine life along certain portion^ of the British coast one naturalist 

 writes, "I have dredged along a Ijauk of this kind for 30 miles cm our 

 own coast witliout finding a single living form." ' In marked contrast 

 with this barren stretch of sea bottom we find other tracts ahmg the same 

 coast tenanted with a marvelous abundance of life. Just otttside the 

 estuary of the river Mersey in Lancashire, Johnstone reports the average 

 results of several hundred hauls in this portion of the British sea as 

 follows : " Thus the total number of animals captured per haul was about 

 12,000 and very often much larger catches than this were made." ^ 



It does not appear that dej^th was a factor in jiroducing the very great 

 contrasts in the abundance of life in these two areas of the same sea. 

 They were due chiefly, if not entirely, to different types of sea bottom and 



•Goodwin-Austin: Natural History of the European Seas, 1859, p. 233. 

 -Johnstone, Jas.: Conditions of life in the sea, 1908, p. 176. 



