THE AMERICAN 



MONTHLY 



V 



MICROSCOPICAL JOURNAL. 



Vol. IX. APRIL, 1888. No. 4. 



A generic synopsis of the sedentary fresh-water Peritricha. 



AN ELEMENTARY CHAPTER FOR BEGINNERS. 



By Dr. ALFRED C. STOKES, 



TRENTON, N J. 



Stein, the eminent German investigator of the infusoria, has classified the 

 ciliated animalcules into four orders, thereby making an arrangement of these 

 little creatures which is so natural and so satisfactory that it will probably 

 always remain the accepted method of grouping them. This system, which 

 depends upon the character and the mode of distribution of the cilia that 

 more or less completely clothe the infusorian's body, may be concisely pre- 

 sented in tabulated form as follows : — 

 I. Cilia clothing the entire surface, and differing but slightly or not at all 



in size Holotricha. 



II. Cilia clothing the entire surface, but those about the oral aperture 

 (mouth) noticeably larger Heterotricha. 



III. Cilia limited to one or more wreaths around the anterior or posterior 



extremities, or both, the rest of the body-surface entirely naked, or 

 with an equatorial locomotive circlet Peritricha. 



IV. Cilia confined to the anterior border, and the lower (venti^al) surface ; 



upper (dorsal) aspect naked ; body usually flattened, Hypotricha. 

 The members of these orders are among the most abundant of the infu- 

 soria. In vegetable and animal infusions they swarm in countless thousands. 

 In the summer pool, the ditch, the mill-pond or the shallow lake, they are, 

 as a rule, more frequently met with than are those animalcules which have 

 been grouped together under the Flagellata of Ehrenberg, or the Tentaculif- 

 era of Huxley (the Acinetaria of Lankester) . They are also the largest, 

 some being distinctly visible to the unassisted eye of the trained observer, 



Explanation of the Plate. 



Fig. I.— Gerda vernalis. Fig. 14. — Thuricolopsis innixa. Zooid contracted; 



-Scyphidia constricta. valve closed. 



3. — Spirochona tintinnabulum (after Kent). 15 



4. — Rhabdostyla vernalis. i6 



5. — Opisthostyla pusilla. 



6. — Pyxidium urceolatum. 17 



7. — Vorticella aquae-dulcis. 



8. — Carchesium epistylidis (after Kent from 



C. & L.) 

 9. — Zoothamnium. Pedicle showing continuous 19, 



muscular thread. 20 



10. — Epistylis vaginula. A portion of a large 21 



colony. 

 II.— Opercularlaplicatilis. Single zooid showing 22 



membrane beneath the ciliary disc. 23 



-Cothurnia imberbis (after Kent). 

 — Pyxicola constricta. Showing operculum ; 

 zooid contracted. 

 Stylocola striata (from Kent after De 

 From.) 

 — Pachytrocha cothurnoides. Showing fleshy 



operculum (after Kent). 

 — Stylohedra lenticula (after Kellicott). 

 — Platycola decumbens (after Kent). 

 — Lagenophrys obovata. An empty lorica on 



a bristle of an Kntomostracan. 

 — Ophionella picta (after Kent). 

 Ophrydium. A small portion of a colony 



12. — Vaginicola leptosoma. enlarged (after Kent). 



13. — Thuricola valvata. Valve closed on the 24 and 25. — Ophrydium. Colonies, natural size 



contracted zooids (after Kent). (from Kent alter Ehrenberg). 



