73 



ten inches in length. In one specimen there are five large branches with 

 several smaller ones between them. They are all in contact and all curved 

 in the same direction. English Head ; H. R. J. Richardson. 



Genus S^richnites, N. G. 



The tracks, for which the above generic name is proposed, consist of 

 two parallel rows of semi-circular or sub-quadrate pits, each pit about half 

 an inch in diameter, usually a little more, and separated from the succeed- 

 ing one about a quarter of an inch. They alternate with each other, uni- 

 formly, in such a manner that the centre of each pit is opposite the space 

 between two pits in the other row. The pits are somewhat curved in out- 

 line on the outer margin, the anterior and posterior margins nearly 

 straight ; the bottom nearly flat, deeply impressed at the outer edge and 

 becoming gradually more shallow to the inner edge where it runs out on the 

 surface. There is a rounded ridge between the two rows of impressions 

 which, however, is not elevated above the general surface. On one of 

 these ridges an obscure median groove can be perceived. The foot ? by 

 which these impressions were made appears to have had a nearly flat 

 bottom, or sole, with the outer margin somewhat sharp edged. The depth 

 of the pits at the outer edge varies from one to sLx lines, usually about 

 four lines. The width of the double rows of impressions varies from fifteen 

 lines to twenty-four lines. The length of the tracks from ten to eighteen 

 inches. In general they are more abruptly terminated and more deeply 

 impressed at one extremity than at the other. 



That these impressions are the tracks of an animal no one, accustomed 

 to the aspect of fossil remains, who examines them carefully can doubt. To 

 whatever class it may yet be referred it is evident that the creature had 

 very short or rudimentary organs of locomotion. A molluscous animal 

 with a foot flat on the bottom, with the median line quite soft and the 

 lateral edges of a gristly consistence could by alternately moving each side 

 make such tracks as these. I do not think they are the trails of trilobites. 

 It is more probable that some of Jhe species of Cephalopoda which swarmed 

 in the Silurian seas could crawl along and make foot-prints in the soft ooze 

 of the bottom of the ocean. There appears to be but one species for which 

 the following name is proposed. 



S. ABRUPTUS, n. sp. — The specific characters are contained in the above 

 generic description. It occurs at Otter or Indian cove near English Head 

 229 feet above the lowest rocks observed on the Island. Also at Macastey 

 Mountain and Observation Bay in the same horizon. H. R. J. Richardson. 



These tracks are so numerous that in some places scarcely a square yard 

 of the surface of the stratum in which they occur is without them. 



