556 DESCEiPTioN OF {Tolygaslrica. 



Its discoid body would rather place it in the Trichodiscus of 

 Ehrenberg. 



AcTiNOPHEYS granota {THclwda granata, M.) — Body globular, 

 opaque at its centre, surrounded by rays of less length than its own 

 diameter. 



Genus Trichodiscus. The rayed-disc Animalcules. — Body de- 

 pressed, with a single marginal row of setaceous tentacles ; vibratile 

 cilia, and teeth absent ; no pedicle ; mouth truncated (direct.) 



These Infusoria, by their flat disciform shape, resemble the genus 

 Arcella, but, luilike the latter, are soft and shell-less, with stiff 

 bristle-like rays. A central opening, and a large lateral gland, have 

 been recorded by Ehrenberg, who likewise states that he has seen, 

 though indistinctly, numerous digestive cells, but neither the re- 

 ception of coloured food, nor the anal orifice. 



T. sol. {Adinophrys Discus, D.) Eigs. 267 and 268. — Body de- 

 pressed, almost flat, hyaHne or yellowish, with variable rays. The 

 motion of this species is very sluggish ; it often remains for a long 

 time inert. Eound amongst Conferva. Diameter, without rays, 

 1 -430th to 1-2 10th. 



Genus Podopheta. The pedicled and rayed Animalcules. — Enchelia, 

 devoid of vibrating cUia and teeth ; their bodies are spherical, and 

 covered with setaceous tentacles ; mouth tnincated (direct.) In 

 organization they are similar to Actinophrys, with a stiff stalk. 



P. fxa {Trichoda fixa, M. — Adinophrys pedicellata, D.) — Has a 

 spherical, turbid, whitish body, with a diaphanous pedicle, slightly 

 excised at the extremity. The rays or setfe have theii- extremities 

 capitate, and equal the diameter of the body in length, as represented 

 at figs. 269, 270 : the latter exhibits it with two animalcules it has 

 seized. Ehrenberg states, the seizing or catching power of this 

 animalcule is very iateresting to observe. So soon as a quickly 

 vibrating Trichodina grandinella approaches to and comes in contact 

 with, its tentacula, it is immediately taken prisoner, ceases to vibrate, 

 and stretches out its cilia backwards. On the whole, this species 

 resembles Acinda, fi-om which it is separated by Dr. Ehrenberg, who 

 supposes it to possess a discharging orifice, though its situation is 

 imknown. Found among dust-lUce matter upon the surface of pond 



