102 PROCEEDINGS OF THE AMERICAN ACADEMY. 



which I have examples, kindly sent me by tin- late Sir J. W. Dawson. 

 It is also different from any British species figured by Wheelton Hind in 

 his elaborate monograph. Desirous of comparing our specimens with 

 types from Nova Scotia, I applied to I >r. <i. .M. Dawson, Director of the 

 Geological Survey of Canada, who very kindly Benl me specimens from 

 the museum of the Survey, labelled in Sir J. W. Dawson's own hand- 

 writing, from Sydney, ('. 1>. I can see no specific differences, although 

 the Sydney examples are casts in a rather coarse micaceous sandstone, a 

 less favorable medium for the preservation of specific marks ; but the 

 general shape and proportions of the valves are the same. The Sydney 

 examples are small specimens from 8 to 14 mm. in length ; each end is 

 much alike, and the beaks are plainly situated at the anterior J-J <>f the 

 shell; in the largest one at the anterior third. In Fig. 1, A represents a 

 large, and />' a much smaller specimen in the pebble found by Mr. Clark, 

 and Ca specimen intermediate in size found in place by Prof. Gorham. 

 All are drawn to the same scale and are enlarged. 



Track of a gastropod mollusc f Pawtucket plant beds. (Scholfield) 

 Proc. liost. Sue. Nat Hist., xxiv., p. 21"). This track is, of course, doubt- 

 ful, and might have beeu made by a worm. 



Merostomata. 



Protichnites narragansettensis, n. sp. This name is given to a new 

 kindof track discovered in a pebble of dark arenaceous shale taken from a 

 kame in north Providence by one of my class, Mr. II. II. Mason. It is 

 allied to ami evidently made by a species of perhaps the same group as 

 made the tracks described as Protichnites octonotatus Owen, and /'. /«/"- 

 minus Marsh from the Cambrian. Description and figures are reserved 

 tor a future occasion. 



Crustacea. 



Remains "f 'a Crustacean^ Three fragments of the remains of what 

 appears to he a macrurous crustacean were found in the black shales of 

 Valley Falls by Mr. Clarke, associated with the leaves of Calamites. The 

 better preserved fragment is square at the base, with one side produced 

 above and ending squarely; the lower corners are truncated. On the 

 lower edge of this fragment is a distinct raised boss or tubercle, while 



the two other fragments are not thus marked. The plates remind one 

 of the epimerum of a shrimp, which is wider on the ventral edge than 

 above. The surface is polished but has not the markings "fa Pandalus. 

 The surface is however marked with very fine irregular raised lines 



