324 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.45. 



original state or the surface worn off by attrition. The mold of the 

 interior shows faint radii, apparently more numerous than on the 

 other specimens. Some of the radii bifurcate. They are too indis- 

 tinct to be counted, but over the central part they are arranged more 

 closely together than on the corresponding surface of the other 

 specimens. The dimensions are 13 by 10 mm. The umbonal portion 

 is low, but the beak is slightly pointed. The body is at first 

 flattened, tapering off gradually to the cardinal angles, but is swollen 

 in the center and arched over toward the front. The specimen is 

 imperfect, but the cardinal angle appears to have been slightly 

 mucronate, and the characters thus suggest its relationship to the 

 form described as Leptsena Isevigata, or Chonetes lepisma, by Sowerby. 

 I refer it provisionally to Chonetes lepisma. , 



Specimen No. M1483.3 is a mold of the exterior of a pedicle valve 

 showing the spines faintly, 4 in number. The umbonal region is 

 depressed and the center part swollen slightly, with a broad shallow 

 furrow down the center. The sides flatten toward the cardinal 

 angles. The radii, which occasionally bifurcate, are quite distinct 

 o^ev the right half of the specimen, 25 of which can be counted from 

 the cardinal angle to the central line, making (if the same on the 

 other half) 50 radii. The dimensions are 12 by 7^ mm. 



OJionetes edmundsi H. S. Williams, types. The specimens Ml 158, 

 1483.1 and 3 present closely similar characters, and to the types 

 I apply the name Chonetes edmundsi. They are longer than typical 

 specimens of Chonetes cornuta Hall, and have a greater number of 

 radii. They also resemble Chonetes tenuistriata Hall, but have less 

 number of radii. They also closely resemble the forms from the 

 Pentland Hills referred to Chonetes striatella by Davidson, of which 

 Davidson says, "the Scottish specimens heing much smaller than those 

 which occur in England and in Sweden' ' (p. 21), as is also shown by 

 the figures,^ of which the dimensions given in the description are, 

 length 2, width 3 lines. 



While it is probable that this Pentland species is the same as our 

 Chonetes edmundsi, my definition is based upon our specimens, and I 

 assign to it a new specific name, which may include the small forms 

 referred to Chonetes striatella by Davidson. 



Another series of the same form coming from loc. No. 8.1.8A is 

 numbered M1556.1-4. 



Specimen No. M1556.1, a mold of the exterior of a pedicle valve, 

 dimensions 11 by 6 mm., shows well-developed umbones, arching up 

 rapidly from the cardinal margin, -wdth broad convex body and the 

 sides exhibiting only a small flattened area at cardinal angles. The 

 radii, of which there are about 80 at the margin, bifurcate more 



I pi. 3, figs. 14, 14a and 146. 



