GUIDE TO LOCALITIES. 



Mytilus edulis, Modiola modiolus, Ostren boreal is (0. Virginiana), 

 Fusus decemcostatus (= Chrysodomus decemco status), Buccinum 

 jjlicosum (= Urosalpinx cinerea), B. trivittatum (=Trifia trivitta- 

 tum). All these were found alive by dredging within a mile of 

 the locality. The outcrop of the shell beds is fifty or sixty feet 

 above the sea level, and the shells are mostly broken and often 

 finely comminuted. Numerous specimens have been collected 

 since from this and other drift sections in Boston harbor by 

 Upham, Dodge, Herman, Crosby and others, who brought the 

 number of species up to thirty-four previous to 1894. In that 

 year, Prof. W. 0. Crosby and Miss Hetty 0. Ballard published 

 a joint paper on the drift fossils, in which were embodied the 

 results of a careful study of collections made by them with the 

 assistance of several students of the Institute of Technology 

 As a result of these studies, the number of species was brought 

 up to fifty-five, and the number of localities to twenty-four. The 

 most important of these localities, with the number of species 

 found in each are as follows : 



Route. — By rail, Boston and Maine^railroad, North Union station, to 

 Gloucester (see p. 15). About three hundred yards south of the Pavilion 

 hotel (Gloucester), and between that building and a small earthwork bat- 

 tery known as Stage Fort, is an exposure In a cliff about twenty-five feet 

 high, in which the fossils were found. Professor Shaler states that this 

 exposure is again accessible. ' 



This section was studied by Shaler in 1868, who reported the 

 cliff as consisting at the base of " close grained, much indurated 

 sands, which have acquired compactness by their own weight 

 without the influence of other metamorphic action." About ten 

 feet above high-water mark are some thin layers of a more 



