CHAPTER IV. 



Belcher's Chorus — Nuttall's Hornmouth — Another 

 Hornmouth — What is Meant by Species — Compared 

 to the Colors op the Rainbow — The Unicorn 

 Shells — Why Shore Shells are so Strong — Advice 

 to Observers — Tyrian Purple — The Rock Purple — 

 Its Varieties — The Grooved Purple — The Wrinkled 

 Purple. 



THE large mollusk whose shell is shown in Fig. 7 

 is such a lover of the warm waters which bathe 



the coast of Southern California, that it never migrates 



far to the north, but is 

 found in the vicinity of 

 San Diego. The engra- 

 ving is of about half the 

 length of a good sized 

 specimen, though some of 

 these shells are found 

 which are fully six inches 

 long. It may sometimes 

 be picked up upon mud 

 flats at the time of low 

 tide. Its name is Chorus 

 Belcher i, Hds., Ko'-rus 

 Belch/-er-i, or Belcher's 

 Chorus. The shell as a 

 whole is somewhat pear- 

 shaped, ending in a long 

 Fi s- 7- canal, to the left of which 



is a deep, funnel-shaped umbilicus. The spire is 



