TOP-SHELLS. 79 



aperture nearly circular. It is yellowish brown in 

 color, and is about the size of a small pea. 



Margarita acuticostata, Cpr., a-cu-ti-cos-ta'-ta is 

 like the last, but much smaller. It is a southern 

 shell, and its surface is marked with a few sharp 

 ridges and some clouded painting. 



Margarita helicina, Mont., hel-i-si'-na, is a third 

 species, and may be briefly described as follows: Spire 

 low, few-whorled, aperture circular, umbilicus small, 

 whorls smooth, color whitish. It is less than one- 

 fourth of an inch in diameter, and its home is in the 

 far north, on the shores of Alaska. It is widely dis- 

 tributed, and is described as circumboreal. 



Gibbula parcipicta, Cpr., Gib'-bu-la par-si-pik'-ta, 

 has a turban-shaped shell, marked with small ridges. 

 The outside is dark or spotted, but the interior is 

 of beautiful green pearl. Its diameter is about one- 

 eighth of an inch. It is a northern species. 



Gibbula succincta, Cpr., suk-sink'-ta, has a very 

 small shell, marked with delicate ridges, and brown, 

 spiral pencilings. 



Calliostoma annulatum, Mart. , Cal-li-os'-to-ma an- 

 nu-la'-tum, Fig. 64. The shell of 

 this mollusk is one of the most 

 beautiful products of this Western 

 Ocean. Regularly conical in shape, 

 sometimes more tapering than is 

 shown in the engraving, delicate 

 in texture, the sutures marked 

 with a rich line of purple, and the 

 Flg - 64 - whorls traced with rows of sculp- 



tured points, it is a shell to be much admired, and to 

 be highly prized. 



