196 



Johannian division of the St. John terrane. But as Mr. Walcott has 

 obtained some excellent material of this species, showing it far better than 

 the original material from St. John, I have adopted the above as a good 

 description of the species. Some differences however may be noted. 



I have found the visceral cavity of the ventral valve extended well into 

 the anterior half of the shell, and that of the dorsal two thirds of the 

 length of that valve. 



The foundation of the ornamentation in this shell is a rough scabrous 

 or granulated surface (with a tendency to develop anastomosing ridges 

 as in Acrothele) ; toward the beak it seldom has other character, but at 

 the middle and towards the front this surface is thrown into concentric 

 ridges, not all regularly placed, but becoming more regular toward the 

 front. Over the middle third these ridges are crossed by radiating ridges 

 of nearly equal strength. On the middle of the valve there are about 7 

 to 9 of the concentric ridges in the space of 2 mm. In this they differ 

 from the examples of the species from the St. John locality in which 

 these ridges are much closer, and they are also more regular. 



The arrangement of the muscle scars and form of the callus in this 

 species is that of Lingulepis rather than of Lingulella. The great 

 inequality of the length of the valves separates it widely from Obolus, in 

 in which the cardinal area of the dorsal valve is high, and nearly equal 

 to that of the ventral. 



The back of the dorsal valve in this species seems to be subject to 

 resorption ; or else no growth takes place there, as the ends of the growth 

 lines at the hinge are far separated from each other. 



The following are dimensions of a few valves of this species. 



DIMENSIONS OP VALVES OF LINGULSPIS STARRI B'ROM BAND C. 2. 6. 



Dimensions of 

 the valves of 

 L. Starri, var. 





