NO. 2144. NEW BRACHI0P0D8 FROM MAINE— WILLIAMS. 79 



EXPLANATION OF PLATE 1. 



All the figures are natural size except figures 2 and 24 magnified 2 diameters, and figure 

 magnified 3 diameters. 



Spvrifer trescotti Williams. 



Fig. 1. Mold of the interior of a mature pedicle valve showing the plica- 

 tions, dental plates, and median septum. 



Fig. 2. An immature specimen of the brachial valve, enlarged two diam- 

 eters (shown natural size on lower left hand corner of fig. 4). This 

 specimen shows resemblance to Spirifer crispus Hisinger. 



Fig. 3. Mold of the interior of a mature pedicle valve. 



Fig. 4. Molds of the interior of the beak portion of a mature pedicle valve 

 and of an immature brachial valve. (See fig. 2.) The pedicle valve 

 shows the dental plates and median septum. 



Fig. 5. A small specimen showing the brachial valve and hinge area of the 

 pedicle valve drawn from a gutta-percha impression. The beak of the 

 pedicle valve is less developed than in mature shells. 



Fig. 6. Mold of the interior of a pedicle valve not fully mature. The 

 center of view is higher up on the umbonal portion of the shell than 

 for figure 1, causing the shell to appear shorter from beak to front 

 than normal. 



Fig. 7. Mold of the exterior of a pedicle valve showing the rounded plica- 

 tions crossed by fine concentric lines. 



Figs. 8 and 11. Two views of mold of the interior of a brachial valve show- 

 ing the number and form of the plications, the rounded median fold, 

 and the form of the hinge border. 



Fig. 9. Mold of the interior of a small brachial valve magnified three 

 diameters. 



Fig. 20. Interior cardinal view of a pedicle valve, showing the triangular 

 area rounded off at sides, the narrow delthyrium, and the edge of the 

 median septiun where the beak is broken off. 



Fig. 22. End view of same specimen as figure 20. 



Fig. 23. Another view of same specimen, showing plications and contour of 

 the pedicle valve. 



Fig. 25. A slightly crushed brachial valve. 



Formation. — Edmunds formation of the Silurian. 



Locality. — Northeast corner of Crowe Necke, Trescott township, Washing- 

 ton County, Maine. 



Spirifer rohscooki Williams. 



Fig. 10. Mold of the interior of a pedicle valve of ordinary size, showing 

 the five well-developed plications, each side the sinus, the absence of a 

 median septum and the short development of the dental plates. 



Fig. 12. Mold of the interior of a mature brachial valve, showing the plica- 

 tions and the well-developed furrow in the middle of the fold and ex- 

 tending fiom beak to front. 



Fig. 21. Cardinal view of a specimen, showing both valves, the high over- 

 arching area and beak, the triangular delthyrium, absence of a median 

 septum in pedicle valve, and trace of the furrow along the top of the 

 brachial fold. 



