110 P. E. Raymond — Seaside Notes. 



which must have been made by short and not elongated 

 animals. Investigations on the sandy beaches during the 

 last few years have shown that whenever a trail-making 

 animal can be identified, it invariably turns out to be 

 something other than a worm. One of the most tortuous 

 of the worm-like trails, seen usually in the troughs of rip- 

 ple marks, is made by a small amphipod which travels 

 about just beneath the surface of the sand. 



One frequently sees on the mud by the roadside trails 

 of the common earthworms. These are usually nearly 

 straight, or in curves of long radius. Doubtless marine 

 chaetopods may come to the surface and crawl along, but 

 I have not seen such trails on the beaches near Boston. 



The most common trail seen in this vicinity is that 

 made by the omnipresent gastropod, Littorina litorea. 

 These animals live on those parts of the beach where there 

 are rocks or other substances to which to cling, and 

 during the time of ebbing of the tide, many of them crawl 

 across the wet sand. The trail which they leave is 

 generally a little wider than the transverse diameter of 

 the aperture of the shell, is bounded by a pair of lateral 

 ridges, and marked transversely by ridges which are 

 bowed forward in the direction in which the animal 

 travels. In creeping along, the outer lower part of the 

 lip is directed forward and the spire points backward to 

 the right. When moving forward the sand is pushed up 

 in a little ridge ahead of the animal, then the shell is 

 raised somewhat and pushed over the mound in front, so 

 that the ridge is preserved even after the Littorina has 

 crawled over it. 



The trails vary a great deal according to the firmness 

 of the sand. When the animal travels through water the 

 lateral ridges are usually high and broad and the trans- 

 verse ones are not seen at all. On very firm sand neither 

 set of ridges is made, so that there is much change in the 

 character of the trail from one point to another as it 

 leads over the various inequalities of the rocky and 

 rippled beach. 



The course in the case of Littorina is usually quite 

 straight except for deviations due to the various obstacles 

 encountered, but the animals do sometimes wander rather 

 aimlessly and make a considerably curved trail. One 

 marking made by a Littorina was 13 feet long, and, to the 



