404 B. S. Lull — Life of the Connecticut Trias. 



throw light upon past climatic conditions, include the remains 

 of at least two species of shells, both belonging to the fresh- 

 water Unionidse, which preclude the possibility of saline tidal 

 waters, at least in the neighborhood of Wilbraham, Massa- 

 chusetts, a locality which, unfortunately for the estuarine theory 

 of origin, is far to the south of places where the sediment 

 would seem to demand the strongest tides. On the other 

 hand, the presence of shells implies more or less permanent 

 waters, either in slow moving or impounded condition. The 

 one insect reported from the valley is found in great abund- 

 ance at Turners Falls, Massachusetts, and has been described 

 as the aquatic larva of a neuropterous insect, hence again 

 implying the presence of waters of some duration. If the 

 period of larval life was equivalent to that of the ephemerids 

 of to-day, the water must have continued not one season but 

 three ; this may, however, have been an annual insect the 

 larval life of which would require but a transitory stream. 

 The invertebrate trails show no characters which would debar 

 them from such a climatic environment as Earrell has assumed 

 for the Connecticut Triassic. 



Fishes are, with the exception of one crossopterygian, all 

 ganoids. And, while confined stratigraphically to two or three 

 black shale bands, their geographical range is from Turners 

 Falls to New Haven. They are, however, all of fresh- water 

 affinities, and may well represent the recurrence of climatic 

 cycles of greater than average humidity and consequent expan- 

 sion of the aquatic habitat, or a disturbance of the drainage, 

 due to volcanic damming or deformation, the climatic condi- 

 tions remaining constant. 



Over the terrestrial vertebrates, aside from a few of the 

 forms unquestionably dinosaurian, so deep a shadow of obscur- 

 ity rests that safe conclusions may hardly be drawn. There is 

 no reason to suppose that all are reptilian; and, if the Amphibia 

 of that day were of similar constitution to the present-day 

 descendants, to whom a one per cent solution of salt is fatal, the 

 proof of their presence would preclude the possibility of 

 marine waters, and add their evidence in favor of continental 

 deposition to that of the lower forms. There are, however, 

 stegocephalians known from brackish water deposits. 



On the Laramie plains in 1899, when conditions were dry 

 even for a semi-arid climate, I found in the dust of the ground 

 within the tent a large and lively salamander of brilliant color- 

 ing whose advent and departure were alike mysterious. Yan 

 Dyke in his description of the desert remarks that all desert 

 trails run in straight lines, showing the animal to be not prowl- 

 ing but intent in getting across to the mountain. The same is 

 true of the fossil trails of the Connecticut valley ; and from the 



