344 AMERICAN JOURNAL 



8. H. Traskii, Newc. 



This shell, nearly allied to the preceding, extends from Los 

 Angelos, north, to Fort Tejon, a distance of about 140 miles. 



The distinctive characters are, the finely impressed and 

 crowded transverse striae, its lighter coloration, more channelled 

 suture, and differences in the animal. 



9. H. HiLLEBRANDi, Newc. 



This interesting shell has been found in Tuolumne Co. by 

 Mr, Voy, and in Mariposa Co. by Mr. Gabb. In recent speci- 

 mens, in fine condition, the epidermis covers the shell so as to 

 •prevent the bands from being seen. The short, rigid hairs on 

 the surface extend through this epidermis, so as to leave cica- 

 trices on the shell, when stripped of this covering. 



10. H. EXARATA, Pfr. 



Upon travelling north from the locality of S. Dupetithouarsii, 

 we pass into Santa Cruz Co., where this species first appears 

 and is found in considerable abundance. We occasionally 

 meet with a variety of a creamy- white color, without bands. 



11. H. RAMENTOSA, Gould. 



This species is met with on the Coast Range of Mountains 

 from the Mission of San Jose to Oakland, and is found at Mare 

 Island, and at the Geyser's or Boiliug Springs, in ISTapa Co. It 

 includes the variety described by Dr. Pfeifi'er as H. reticulata. 

 Dr. Gould's description dates Oct., 1856, Dr. Pfeiflfer's in 1857. 

 There are several varieties of this species, the typical specimens 

 having more solidity than those from the Geyser's and Mare 

 Island ; the latter having the columella of a flesh color, and the 

 whole shell of a light corneous texture. An extreme variety 

 in size, of which but a single specimen has been found, 

 measures in greatest diameter 1'30 inch, while the smallest 

 adult in my collection measures but "70. The table of measure- 

 ments attached to this communication, giving the extremes of 

 different species, will be of service in indicating the range of 

 variation in size. 



12. H. Bridgesii, Newc. 



This species has been found only in the neighborhood of 

 San Pablo, in Contra Costa Co. It has the sculpture of ramen- 

 tosa, but finer, and the form of Nickliniana, but with a more 

 oblique aperture and more pointed and elevated spire. It is 

 not so widely separated from either of the two as to claim first 

 rank as a distinct species, but will, under the rules of Prof. C. 

 B. Adams, claim a second place in his proposed system of 

 classification. 



