PETRICOLA DACTYLUS. 



DESCUIPTION. 



Shell transversely oblong-oval, white, with radiating 

 raised striae, which on the posterior half of the shell, from 

 twelve to eighteen in number are larger, and approximate, 

 those of the anterior portion of the shell filiform, the trans- 

 verse striae are undulated on the anterior part of the shell ; 

 basal margin arquated ; tedfi two in the right valve and 

 one prominent one in the left. 



6YK0NYM. 



P. DACTYLUS, <Sbt^er6i/'s Genera^ pi. Petricola, fig. 3- 



OBSEHVATIONS. 



For this species I am indebted to the kindness of Dr> 

 Ravenel, who distinguished it from the preceding as a sepa- 

 rate species. The largest specimen in my passession mea- 

 sures nearly two inches in breadth. It resembles the pho- 

 ladiformis but is a more robust shell, being less transverse- 

 ly elongated, the base more arquated, the larger striae are 

 more numerous and destitute of vaulted scales and the 

 teeth are quite different. 1 had distinguished it by the 

 name of flagellata, but on a more close comparison with 

 Sowerby's figure and very short description in which no 

 locality is given, it evidently approaches that species and 

 is probably identical. 



PI. 60. 



