138 BULLETIN 68^ UNITED STATES NATIONAL MUSEUM. 



All spiral cords between the sutures nodulose — Continued. 

 Sutures not channeled. 



Axial ribs always stronger than the spiral cords tyleri, p. 157. 



Axial ribs not as strong as the spiral cords. 

 Spiral cords 4 between the sutures. 



Adult shell more than 5 mm. long scammonensis, p. 158. 



Adult shell 3 or less mm. long. 



Basal cords 4 pulchra, p. 158. 



Basal cords 6. 



Spaces between the spiral cords deep, broad channels. 



montereyensis, p. 159. 

 Spaces between the spiral cords mere impressed lines. 



pulcia, p. 160. 



Basal cords 10 or more virginalis, p. 160. 



Spiral cords 5 between the sutures defoJinia, p. 161. 



Spiral cords more than 5 between the sutures. 



Basal cords 6 oregonensis, p. 1G2. 



Basal cords 10 or more virginalis, p. 160. 



All spiral cords between the sutures not nodulose. 



Anterior spiral cord between the sutures smooth and wholly exposed, the rest 

 nodulose. 



Nodulous spiral cords 4 between the sutures. 



Shell large, adult more than 4.5 mm. long benthina, p. 163. 



Shell small, adult less than 3 mm. long promeces, p. 164. 



Nodulose spiral cords 3 between the sutvu-es. 



Shell large, adult 5 mm. long pulcherrima, p. 164. 



Shell small, adult less than 3 mm. long. 



Basal cords 5 vincta, p. 165. 



Basal cords 6 fasciata, p. 165. 



Anterior half of the whorls between the sutures usually not nodulous, the rest 



strongly so virginalis, p. 160. 



Early whorls and frequently only the posterior part of these nodulose. 



Shell long, adult more than 4 mm. long helga, p. 166. 



Shell small, adult less than 3 mm. long. 



Base decidedly attenuated anteriorly sanctorum, p. 167. 



Base not strongly attenuated. 



Spiral cords 6 between the sutures sapia, p. 167. 



Spiral cords less than 6 between the sutures. 



Spiral cords very strong rotundata, p. 168. 



Spiral cords almost obsolete deceptrix, p. 169. 



ODOSTOMIA (CHRYSALLIDA) REIGENI Carpenter. 



Plate 13, hg. 7. 



Chrysallida reigeni Carpenter, Cat. Mazatlan Shells, 1856, p. 422. 



Shell elongate-ovate. Nuclear whorls smooth, deeply immersed in 

 the first of the succeeding turns. Post-nuclear whorls flattened, 

 strongly contracted at the sutures and well shouldered at the sum- 

 mit, marked by strong axial ribs of which 18 occur upon the first 

 and 20 upon the second and penultimate turn. In addition to the 

 axial ribs, the intercostal spaces, which equal the ribs in width, are 

 marked by four slender spiral cords between the sutures, which pass 



