NO. 2225. NUCULITES FROM THE MAINE SILURIAN— WILLIAMS. 57 



12. An internal cast of a left valve (M 1786 D). In this specimen the strong clavicle 

 is in evidence, but the internal ridge separating the umbonal cavity from the posterior 

 muscular scar is wanting. The figure showing the external surface of this species (pi. 

 11, fig. 9) was made from the impression of the exterior of this same specimen, and the 

 drawing of the hinge teeth enlarged represented by figiu*e 14 is also made from this 

 specimen. 



Locality. — Same as figure 4 (loc. No. 5.25.4 B). 



14. An enlarged drawing of the hinge border and its teeth made from the internal 

 mold (fig. 12) on a scale to compare with the hinge of Tindaria reproduced in the figure 

 1 immediately above it. 



Locality. — Same as figure 4 (loc. No. 5.25.4 B). 



15. An umbonal view of a left valve associated with the other specimens of this 

 species. Introduced to show the effect of changing the point of view in preparing 

 illustrations (M 1781). 



Locality. — -Same as figure 4 (loc. No. 5.25.4 B). 



Nuculites chrysippus Williams. 



Fig. 5. A specimen of the right valve, oriented on the plate as seems consistent with 

 the development of the lines of growth. If it were turned on its center about 20 

 degrees to the right, its characteristic form would be obscured. (M 1787). 



Locality. — Pembroke splintery shales in the southern part of West Pembroke on 

 west side of Pennamaquam Puver (loc. No. 1.45.6 A). 



Nuculites lentus Williams. 



Fig. 6. The two valves of a single specimen as originally attached at the hinge line. 

 The much narrower and elongate form of the right valve than the left is readily 

 explained by the different relation of the two valves to the compressing force which 

 affected the whole rock in which the shell was imbedded (M 1769). 



Locality.— Edmunds shale at north end of Straight Bay near east end of Crowe Neck, 

 Trescott (loc. No. 5.33.8 B). 



13. A detached right valve of apparently normal size and shape (M 1768). 

 Locality.— Same as fig. 6 (loc. No. 5.33.8 B). 



Nuculites subplanus Williams. 



Fig. 8. A magnified portion of the sm'face of the posterior end of the specimen 

 figured on plate 11, figure 17, showing the radiating lines crowning the finer, more 

 closely set concentric lines (M 1765 B). 



Locality. — Edmunds shale formation, at north end of Straight Bay, Crowe Neck, 

 Trescott (loc. No. 5.33.8 B). 



Nuculites spedosus Williams. 



Fig. 9. A right vah'e, of smaller size. The front is rather shorter than in the other 

 examples of this species, showing, however, the normal characters of the posteroir end 

 (M 1806). 



Locality. — Pembroke shales on the west side of Coffin Neck, opposite Gooseberry 

 Island, immediately underlain by shale carrying an Edmunds fauna (loc. No. 5.44.2 A). 



18. A right valve, the basal margin of which is cm'ved inward narrowing the front 

 part of the shell (M 1809). 



Locality. — Pembroke shale at north end of Coffin Neck, Lubec (loc. No. 5.34.7 A^). 



19. A right valve, imperfectly showing the surface characters of the posterior end, 

 but in outline expressing approximately the normal shape (M 1804). 



Locality. — Same as figure 9 (5.44.2 A). 



