HABITS OF LINGULA 



483 





animal has with the world around it is 

 hy means of the currents set up by the 

 cilia, on the tentacles. 



In spite of the absence of any definite 

 eyes, Thecidmm, according to Lacaze- 

 Duthiers, is sensitive to light ; he noticed 

 for instance that, when his shadow fell 

 across a numljer of these animals he was 

 watching in a vessel, their shells, which 

 had been previously gaping, shut up at 

 once. 



In CistcUa the tentacles can be pro- 

 triuled from the open shell, and in Bliyn- 

 chonella the spirally-coiled arms can l:)e 

 unrolled and extruded from the shell, but 

 this does not seem to have Ijeen observed 

 in other genera, with the possible ex- 

 ception of Li /)[/(( la. The f(jod of these 

 animals consists of minute fragments 

 of animal and vegetable matter, a very 

 large proportion of it being diatoms and 

 other small algae. 



Lingula differs markedly from the 

 other members of the group, inasmuch 

 as it is not firmly fixed to a rock or 

 some such body by a stalk or by one of 

 its valves, Init liAes in a tulje in the 

 sand. Some recent observations of 

 Mons. P. Francois ^ on living specimens 

 of LinguUt anatifera which he found Fig. .321.— Figures illustrating 



living in great numbers on the sea- 

 shore at Xoumea in New Caledonia 

 may Ite mentioned. The ]»resence of 

 the animal is shown by a number of 

 elongated trilobed orifices which lead 

 into the tube in wliicli the JAiKjala liA'cs. 

 The animals, like most other l>rachi- 

 opods, live well in ca]itivity, and he was 

 able to watch tlieir liabits in the a(piaria 



^ " Glioses de Noumea," Arch. d. Zool. ex}^. et gen. 2nd ser. vol. ix. 1891. 



the tubes in which Livgula 

 anatifera lives. The ujiper 

 figure is a view of the tri- 

 lobed opening of the tube. 

 The lower figure shows the 

 tube in the sand laid open 

 and the animal exposed. 

 The dotted line indicates 

 the position of the body 

 when retracted. The darker 

 portion is the tube of f>aud 

 .agglutinated by the secre- 

 tion of the stalk, (After 

 Francois. ) 



