f>4 



HABITS of ungula. 



cylindrical specimen jars, in which the mad was so placed as to imitate as 

 far as possible the natural conditions. I buried a specimen deep in the 

 mud, touching the inner wall of the jar in order to observe how it makes 

 its burrow. At first the water is forcibly gushed out of the central 

 funnel formed of the mantle edge and the setae. By this the mud above 

 the animal was gradually removed. By the above action coupled with 

 the sliding lateral motion of the shell, the burrow was soon formed, 

 whose walls were made smoth owing to the secretion of the gland-ridge 

 (Drüsenwall) and to the up-and-down gliding of the valves. Seen from 

 above the burrow gives a rhombic aspect a little larger than the section 

 of the animal. Lingula can extrude itself above half of its shell length 

 from the surface of the mud ; when alarmed it would retire 5-30 cm. 

 below the mud surface according to the size. At that time we can 

 perceive how great the contractibility of the peduncle is. When the 

 animals are dug out of its burrow the peduncle is of the minimum length. 

 The peduncle, it should be noted, of our Lingula is comparatively short. 

 In Glottidia according to Morse, it reaches nine times the shell 

 length. This difference in length of the peduncle can readily be noticed 

 so early as the stage of 7-i) pairs of cirri. 



Some Brachiopods can protrude their arm-apparatus out of the 

 shell as observed by Morse (79). According to him, such is the case 

 in Lingula, (p. -Î57). On the contrary Semper (*<i4) states of the 

 animal "dass Arme niemals zur Schale hervor gestreckt werden und 



sich niemals enrollen " (p. 4'24). To settle 

 this point I placed a number of individuals 

 in a glass vessel and looked at them carefully. 

 At last I found that only the comb-like row 

 of cirri of the largest whorl of the arm 

 can be projected out of the shell as in the 



A. 



cat (A and B) but the tip of the arm- 

 apparatus is always kept within the mantle 

 cavity. The protrusion of the cirri, that is 

 fore-ward and backward movement of the 



