10 



History of Hingham. 



Formations. 



Niagara Period 



Salina Period. 



5 



«2 



Lower Helder- 

 berg Period. 



Oriskany 

 Period. 



Devonian Age. 



Corniferous 



Period. 



Marine only : 



Plants, sea-weeds. 

 Animals, invertebrates. 

 No evidence yet of fishes 

 or of fresh-water life. 



Almost destitute of fossils. 



Fossils of the same generic 

 character generally as 

 in preceding periods, the 

 species distinct. 



Trilobites common, but 

 with them a new Crus- 

 tacean appears for (lie 

 first time, the Euryp- 

 terus remipes, a foot or 

 more in length. 



Plants generally marine. 

 One species of Lijcopo- 

 dium (ground pine) has, 

 however, been found. 



No fishes yet noticed in 

 American beds of this 

 period, but in Europe 

 their remains are met 

 with in the Ludlow 

 rocks, which are equiv- 

 alent to the Lower Hel- 

 derberg and Oriskany of 

 America, and are the 

 first vertebrates yet dis- 

 covered in formations 

 earlier than the De- 

 vonian. 



Of the Class Arachnida: 

 articulated animals having 

 the body generally divided 

 in two parts, as Scorpions, 

 Spiders, Ticks, etc., — the 

 first represented in the 

 earth's formations were 

 found in the Upper Silurian. 

 Three species, all Scorpions. 

 Of the true Insects, one 

 specimen has been found in 

 the Upper Silurian, but the 

 character of this has not 

 been clearly made out. It 

 belongs to one of the orders 

 of the Hexapoda. 



Age of Fishes. 



Marine Plants include a 



new form, the Spirophy- 



ton cauda galli. 



General Remarks. 



The Niagara Period was one of 

 subsidence of the land over ex- 

 tensive regions. 



The rocks of the Salina Period 

 yield salt from brines contained 

 in them. The subsidence men- 

 tioned as occurring during the 

 NiagaraPeriod continued through 

 this. 



The extinction of species during 

 the progress of the Silurian Age 

 was great. ] )ana says, " There is 

 no evidence that a species existed 

 in the later half of the I'pper 

 Silurian that was alive in the 

 later half of the Lower Silurian." 



The greater part of the continent 

 yet remained under water at the 

 close of the Silurian Age. 



There is no evidence that the cli- 

 mate, even in high latitudes, had 

 become otherwise than warm and 

 temperate as in the Lower Si- 

 lurian Periods. 



During the Corniferous Period, a 

 large part of the continent was 

 covered with shallow seas, in 



