746 THE POPULAR SCIENCE MONTHLY. 



family of the Terebratulce, there are two smaller shells on the stone. 

 The smallest species, of which three specimens lie on the middle of 

 the stone, has the form of a heart, which is attached by its point. It 

 shows a few dull-red spots on the middle of the shell, and is named 

 Argiope. The other one, a little larger species, appears at the left in 

 three specimens, with a straight hinge-border, and is broad and firm, 

 and is called Megerlea. 



We placed this piece of stone with its four species of shells, to 

 which others that abound in the Mediterranean might be added, into 

 a pail filled with sea-water, in which several other animals were stir- 

 ring. We intended to watch the life-expressions of these fixed ani- 

 mals. Our patience was exposed to a hard trial. Hours passed 

 away, without our being able to perceive the slightest movement. 

 We had become tired and were yawning, when we thought we per- 

 ceived the little Argiope mocking us. It was, in fact, gaping. 

 The Megerlea, the snake-head terebratula, and the glass terebratula, 

 followed its example and yawned too, but as discreetly as if they 

 were in well-bred society. The valves parted from one another 

 only a little ; a few fine, glassy, glistening hairs, which could only 

 be seen with the glass, appeared outside. That was all. Tere- 

 bratulas have been kept for weeks and months living in glass vessels 

 filled with sea-water, without any other movement being perceived 

 than this gaping, which sometimes continued for hours. When they 

 had gaped enough, they shut their shells, slowly and measuredly, as 

 if they would sleep ; and, when they had slept enough, they gaped 

 again. Old noble by entail, which has grown fast to its estate, and 

 sleeps or gaps its life away ! But what do they feed upon ? A closer 

 investigation was required to find that out. 



The two valves of the shell are not alike. The difference is great- 

 est in the terebratula. One valve is wide, bellied, and runs into an 

 upward-turned beak perforated by a round hole through which passes 

 a short, round stem that is resolved outside of the shell into a bundle 

 of thongs by which the animal fastens itself. The smaller valve rests 

 as a cover upon this one. 



We try to open the valves as they are opened in the gaping, but it 

 is impossible to do it without force ; so we have to break the shell 

 open. Fig. 2 shows the opened snake-head terebratula magnified 

 six times. The bellied valve is filled with two peculiar, half-moon- 

 shaped processes, consisting of two bent, cartilaginous pipes, on the 

 outer side of which stand a number of fringes which wind in a worm- 

 fashion and circulate in constant movement. The space between these 

 great arms, as they are called, includes two smaller arms, provided 

 with similar fringes, which roll up helicoidally toward the bottom. 

 Nearly all the space of the bellied shell is occupied by these forms ; 

 except that above, toward the point of the valve, may be seen some 

 muscles, which open and shut the shell, and conceal from view the 



