Aspidiscina.] THE INFUSORIA. 305 



Family XIX. ASPIDISCINA. 



The animalcules included in this family are distinguished 

 from those in the preceding one by the presence of a shell, 

 or lorica ; they have a distinct alimentary canal with two 

 orifices, the discharging one only being terminal ; the 

 lorica is a firm, very transparent, combustible little shield, 

 somewhat resembling the shell which covers the back of a 

 tortoise; it projects anteriorly a little before the body; 

 long flexible bristle-like organs attached to the abdomen 

 enable the animalcule to climb, while its delicate cilii near 

 the mouth serve as swimming and purveying organs. 

 Numerous stomach-cells have been filled with coloured 

 food by Ehrenberg, who has also seen the discharge of 

 matter posteriorly. In one species ova and an oval gland 

 are seen; in both a contractile vesicle. Miiller observed 

 self-division, but mistook it for copulation. They are not 

 developed in large masses. 



Genus CXIX. Aspidisca. The shield Animalcules. 



505. Aspidisca lynceus (Trichoda lyiiceus, M.) The 

 beaked Aspidisca. — Lorica nearly circular, truncated at the 

 posterior end, and formed into a hook or beak in front. 

 This animalcule generally swims or creeps with its back 

 underwards. The mouth has very delicate cilii ; the body 

 five or six bristles (styles) posteriorly, and from five to 

 eight hooks anteriorly, resembling in this respect Euplotes 

 or Stylonychia. A contractile vesicle near the mouth, and 

 twenty digestive cells, have been seen. When burnt upon 

 platina no traces remain. Found amongst duck-weed and 

 conferva. Size 1-1 000th to 1-57 6th. 



