THE BRACHIOPODS 73 
an opening near the back of the lower shell, or between the shells. 
In some forms this stalk is very small and serves merely to 
attach the creatures to rocks, ete., while in others it is used in bur- 
rowing through sandy beaches. The intestine curves around and 
opens, if at all, on the right side near the mouth. There is a well 
developed liver and one or two pairs.of tubular kidneys, while the 
heart lies above the stomach. 
The Parchment Shell, (Terebratulina septentrionalis, Fig. 45), 
is a Brachiopod, and is extremely abundant off the New England 
coast, on rocky bottoms at depths between 100 and 500 feet, and it 
is also found off the northern coasts of Europe. At first sight it 
resembles a little bivalve with elongate, slightly heart-shaped 
shells, of yellowish color, resembling old parchment The shells 
are marked with faint radiating ridges, and the lower shell projects 
backward beyond the apex of the upper. The Brachiopod is 
attached to rocks, ete., by means of a stalk-like body which projects 
backward through an opening near the narrow apex of the lower 
shell. In life the shells move quite freely over each other and often 
gape open, displaying the beautiful feathered ‘‘arms” or gills which 
he coiled within the cavity of the shells. This little creature is not 
more than an inch long and three-quarters of an inch wide. The 
eggs are laid in the water, and develop into minute free-swimming 
larvee covered with moving cilia, and having a tuft of bristles at 
the head end. The body is pear-shaped, with two constrictions. 
Soon the creature cements itself to the bottom by the posterior end 
of the body, and two folds which are to secrete the shells, one on 
the back and the other on the lower side, grow upward and en- 
close the body. 
