112 P. E. Raymond — Seaside Notes. 



spaced curved lines such as might have been made by the 

 frontal margin of the anterior part of the foot (propo- 

 dium) which is most strongly developed in those gas- 

 tropods which crawl on wet sand, and is apparently 

 pushed ahead to smooth out the path of the animal. 



Nicholson and Etheridge 4 figured the trail made by a 

 recent Purpura, and called attention to the fact that it 

 greatly resembled some of the markings ascribed to 

 annelids. In spite of the evident similarity of this trail 

 to those generally called Nereites, and which are so com- 

 mon in the early Paleozoic rocks of Europe and North 

 America, Nicholson still referred the latter to the Anne- 

 lida. Nereites is a trail with exceedingly numerous and 

 abrupt turnings, and how an elongate animal like a chse- 

 topod could drag itself along and leave so sharp and clean 

 cut an impression is difficult to understand. A short gas- 

 tropod, hitching itself along, and wandering back and 

 forth in search of food, would make just such a trail. 



Hancock 5 was among the first to doubt the vermiceous 

 origin of markings of this nature, and was led by observa- 

 tions on the beaches of Durham, Eng., to ascribe them to 

 the activities of Amphipoda. Trails like that shown on 

 pi. 14, ^g. 1 of Hancock's paper are very common in the 

 hollows between ripples on the beaches about Boston, and 

 are made by small Amphipods. On plate 17 of the same 

 article is represented a trail very like the smaller form 

 described by Dr. Powers in the article accompanying this 

 one. This nodular type of trail was explained by Han- 

 cock as due to the work of an amphipod or other crusta- 

 cean burrowing its way, with frequent periods of rest, 

 through a rather tenacious mud which was strong enough 

 to prevent collapse of the tunnel after the animal had 

 passed through. The nodular character he conceived of 

 as being produced by a deviation of the animal from the 

 horizontal plane, rising and sinking a little at each 

 advance. The specimens which he described seem quite 

 perfect, and do not show any trace of lateral ridges, and 

 hence differ from the trails of gastropods. 



4 Mon. Silurian Foss. Girvan Dist., f asc. Ill ; reproduced in Nicholson & 

 Lydekker, Manual of Palaeontology, ed. 3, 1889, vol. 1, p. 489, fig. 351. 



5 Am. Mag. Nat. Hist., ser. 3, vol. 2, p. 443, 1858. 



