POLYOASTRIA. 



being situated at the opposite extremities of 

 the body; loricated. = Encheliada? furnished 

 with a shell. 



Coleps, (1, 2, fig. 13.) 

 Family 17. TRACHELJNIDJE (Neck 

 Animalcules). Animals polygastric, furnished 

 with a distinct intestinal canal, having an oral 

 and an anal opening, but of these the anal 

 opening onlv is terminal ; without shell. 

 Trachelius, (3, 4, 5, fig. 13.) 

 Loxodes. 

 Bursaria. 

 Spirostoma. 

 Phialina. 

 Glaucoma. 

 Chilodon. 



Nassula, (1, fig. 16.) 



Family 18. OPIIRYOCERCINIDJE (Swan 

 Animalcules). Animals polygastric ; having a 

 distinct intestinal tube, furnished with two 

 openings, that of the mouth only being termi- 

 nal ; without a shell. 



Trachelocerca, (3, 4, fig. 16.) 

 Family 19. ASPIDISCINID^ (Shield 

 Animalcules). Polygastric, loricated, animal- 

 cules ; having an intestinal canal furnished 

 with two orifices, of which one only, viz. the 

 anus, is terminal. 



Aspidisca. 



Family 20. COLPODEAD^E (Breast Ani- 

 malcules). Animals polygastric ; without a 

 shell ; intestinal canal distinct, with two open- 

 ings, neither of which is terminal. 

 Colpoda, (2, 3,/g. 18.) 

 Paramecium, (1, 4, fig. 18.) 

 Amphileptus, (2, Jig. 16.) 

 Uroleptus. 

 Ophryoglena. 



Family 21. OXYTRICHINIDJE (Hackle 

 Animalcules.) Animals polygastric; without 

 shell ; having an intestinal canal with two dis- 

 tinct orifices, neither of which is terminal; pro- 

 vided with vibrating cilia, and also with styles 

 or uncini, which are not vibratile. 

 Oxytricha. 

 Ceratidium. 

 Kerona. 

 Urostyla. 

 Stylonychia. 



Family 22. EUPLOTIDJE. (Boat Ani- 

 malcules.) Animals polygastric, loricated ; 

 with a distinct alimentary canal having two 

 orifices, neither being terminal. = Aspidisca 

 with neither orifice terminal, or Oxytricha pro- 

 vided with a shell. 



Discocephalus. 

 Chlamidodon. 

 Himantophorus. 

 Euplotes, (fig. 19.) 



All the above families are grouped by Ehren- 

 berg under the following orders and sections, 

 which, as it will facilitate the observations of 

 the microscopist, as well as be a convenient 

 guide to us in studying the economy of these 

 little beings, we will subjoin in a tabular form, 

 premising that the illustrious naturalist of 

 Berlin found it advisable to separate the Poly- 

 gastria into two parallel series, one comprising 

 all such as were destitute of a shell (" 



the other embracing those which are furnished 

 with such a covering (LORICATA). 



ANENTEIIA. 



This includes all animalcules which possess 

 neither an internal nutritive tube nor an anal 

 orifice, the mouth being in communication 

 with several nutritive vesicles. These may be 

 divided into the following sections : 



1st Section. GYMNICA. 

 Animalcules whose body has no external 

 cilia nor pseudopediform prolongations. 

 Nuda. Loricuta. 



Monadina. Cryptomonadina. 



Vibrio. Closterina. 



2d Section. EPITRICHA. 

 Exterior of the body ciliated or furnished 

 with seta? and without pseudopediform prolon- 

 gations. 



Nuda. Loricata. 



Cyclidina. Peridinsea. 



3d Section. PSEUDOPODIA. 

 Body provided with variable pseudopediform 

 prolongations. 



Nuda. 

 Amoeba. 



Loricata. 

 Bacillaria. 



SECOND DIVISION. ENTERODELA. 

 This division includes all animalcules having 

 an internal digestive canal provided with a 

 mouth and anal opening. 



4t/i Section. ANOPISTHIA. 

 Mouth and anus contiguous. 



Nuda. Loricata. 



Vorticellina. Ophriclina. 



5t/i Section. ENANTIOTRKT/%. 

 Mouth and anus terminal and opposite ; re- 

 production by transverse division. 



Loricata. 

 Colepina. 

 ALLOTRETA. 



Nuda. 

 Enchelia. 



6th Section. 

 Mouth and anus terminal and opposite, as 

 in the last section ; reproduction by longitudi- 

 nal and transverse division. 



Nuda. Loricata. 



Trachelina. Aspidiscina. 



7th Section. KATOTRETA. 

 Mouth and anus not terminal ; reproduction 

 as in last section. 



Nuda. Loricata. 



Kolpodea. Euplota. 



Oxytrichina. 



Taking the above classification for our gui- 

 dance, we must now proceed to investigate 

 more minutely the organization of the strange 

 animals included in this extensive series. 



Locomotion. Although no special locomo- 

 tive apparatus has as yet been discovered in the 

 family of Monads, this perhaps depends rather 

 upon our deficient means of investigation than 

 upon their absence. Attentive observation 

 shews that every true Monad is furnished 

 with a minute filiform proboscis, (1, 2, 3, 

 Jig. 1,) which, as it constantly exhibits an un- 

 dulatory or vibratory motion, has been mis- 

 taken by some observers for a ciliary apparatus. 

 Sometimes two of these organs are present, but 

 this cannot be regarded as an essential charac- 

 teristic feature, seeing that during the process 

 of spontaneous fissure an animalcule which 

 previously had only one proboscis, becomes 



