Aspidiscina.] TH E 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 lynceus, 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 l-1000th to l-576th. 



