xii OBITUARY NOTICES. 



count-^ of some new Cycads and Conifers which were sent to the 

 museum from the " New Red " formation of Bucks County, Pa., a 

 region with which he had become very famihar during his asso- 

 ciation with Mr. Benjamin Smith Lyman, on the State Survey. 



Another important paper was prepared from data collected on 

 his Labrador trip nine years before, entitled, " The Formation of 

 Ripple Marks, Tracks and Trails."-^ He had found that the broad 

 clay and sand flats of Sandwich Bay, Labrador, which were covered 

 by shallow water at high tide, exhibited wonderful series of ripple 

 marks which bore a striking resemblance to those seen in the 

 Triassic rocks. He immediately began a minute study of the water 

 action in order to ascertain just how they were formed, and dis- 

 covered that they were of two kinds — caused respectively by de- 

 posit and erosion. The many tracks and marks on these clay beds 

 were also carefully studied and many of them proved practically 

 identical with certain tracks and trails in the Connecticut Trias 

 described by Hitchcock as those of annelids, fishes, etc., to which he 

 had given distinctive names on the basis of these tracks. Brown 

 found that a pebble to which a large sea-weed {Ulva) was attached 

 made a perfect " annelid " trail, the sea-weed buoying it up and 

 allowing it to drag slowly along on the bottom. Pieces of other sea- 

 weeds and bits of spruce boughs rolled along by the water pro- 

 duced other tracks, some of which were counterparts of those 

 described as belonging to a supposed jumping animal called " Sal- 

 tator," while the bifid and trifid fruiting tips of Fucoid sea-weeds 

 made tracks strikingly like -those of certain small reptiles. This 

 paper is an excellent example of the clearness of Brown's observa- 

 tion and the activity of his reasoning powers. 



On the Jamaica trips the large land mollusks had attracted his 

 special attention and his first paper on this material dealt with 

 variation in certain species of Pleurodonte.-^ He had made intensive 

 studies of various colonies of each of several species and endeavored 



-1 " New Cycads and Conifers from the Trias of Pennsylvania," ibid., 

 191 1, pp. 17-21. 



22 <"pj^g Formation of Ripple Marks, Tracks and Trails," ibid., 191 1 pp 



536-547- 



23 " Variation in Some Jamaican Species of Pleurodontc," Proc. Acad. 

 Nat. Sci. Phila., 191 1, pp. 1 17-164. 



