elevated ribs extending longitudinally, giving the effect of the strings 

 on a harp, whence the name of the genus (Harpa}. The colors are 

 different shades of brown, which form neat festoons of dark brown 

 lines between the ribs. The inner lip of the shell is marked by a dark 

 brown spot, and another spot is frequently developed near the upper 



part of the whorl. In one species, Harpa rosea, 

 the shell is marked by several rosy spots and 

 tints, which make a very beautiful shell. The 

 animal of this genus is no less interesting 

 than the shell, being variegated with many 

 beautiful colors. The foot is long, crescent- 

 shaped in front, and becomes narrowed to a 

 point behind. The animal is said to voluntarily 

 break off a piece of its foot when irritated, 

 as it is not able to retreat within its shell. 

 It is destitute of an operculurn. It is very 

 active, and crawls about with an easy, graceful 

 motion. Harpa lives only in the tropics, and 

 the Indian and Pacific oceans, and on the west coast of 



Harpa ventricosa, one of 

 the most beautiful of the harp 

 shells. (Tryon.) 



is found in 

 America. 



The bubble shells include among their number many curious and 

 interesting animals. The typical genus, Balla, numbers some fifty 

 species of smooth, globular shells, frequently mottled like a bird's egg. 

 The aperture is as long as the shell, and the outer lip is thin and 

 sharp. The animal is large and fleshy, and partly envelops the shell. 

 The bubble shells love sandy, mud flats, in which they bury them- 

 selves, or find concealment under masses of seaweed. Like many land 

 shells, they exude vast quantities of mucus to moisten 

 their skin when the tide is out. These animals are 

 carnivorous, living on bivalves and snails, which are 

 swallowed whole and reduced to fragments by their 

 huge, calcareous gizzards. 



The species of bubble shells are quite numerous in 

 the waters bordering the Atlantic and the Pacific 

 coasts of the United States, no less than sixty species 

 living on the eastern coast and about thirty species on 

 the western coast. Among the latter the Bidla 

 nebulosa, which attains a length of two inches, is the 

 largest and finest. The eastern species are much smaller, none measur- 

 ing more than an inch in length and many of them being exceedingly 

 minute. Many of the bubble shells are difficult to collect alive with 



104 



A sea hare, 

 lysia depilans. 

 (Tryon.) 



