198 KARL WILHELM GENTHE, 
Bernpr’s observations, I have usually seen the tips of the cirri 
protruded out of the lips as described above in animals in situ as 
well as in those taken out. 
Some more observations seem necessary to make out more 
definitely the significance of the movements of the oral cirri and 
their beating against the cushions of the terminal cirri. With all 
due respect to the careful work of AvrRivinuius and Bernpr I 
cannot help thinking that their explanations are somewhat theoretical 
and unsatisfactory, although I am myself not in a position to offer 
anything better. 
The list of literature on Alcippe is not very long and has been 
given only recently by Brernpt. It seems unnecessary to repeat it. 
Explanation of the Plates. 
Patents 
Fig. 1. Animal in situ in the mollusk shell. 
a Lips of mantle. b dark brown area. c calcareous filling, 
dull white. 4 banded filling in the end of the slit. e “fan- 
shaped’’ spot. 
Fig. 2. Animal in situ. The shell was broken away so as to offer 
a side view of the animal in its boring. 
Fig. 3. A group of six animals crowded together, in situ. 
The ventral portions of the cavities were broken away, the 
animals are still attached to the roofs of their respective borings. 
Fig. 4—6. The same animal in ventral, dorsal, and lateral view. 
ZEIss a* 10, tube drawn in (136 mm), oc. 2 achr. ABBÉ camera. 
The details of the musculature were mostly worked out with 
darkground illumination, though not drawn so. The specimen 
had been killed and preserved in formalin. Measurements: Greatest 
width 3.5 mm; length 5 mm; thickness taken at maximum of 
bulging out disk 2 mm; length of mantle lips 1.5 mm. 
