688 



SYSTEMATIC HISTORY OF THE INFUSORIA. 



tended animalcule^ riglit side ; xxxin. 

 405 another, contracted, with the jaws 

 pushed out.) 1-120" to 1-72". 



D. forcipata ( Vorticella vermicularis, 

 Cercaria forcipata et £. verinicularis, M.) 

 (xL. 24). — Cylindrical, slender, obliquely 

 truncated anteriorly ; toes decurved, and 

 longer than the stout foot. 1-110". 



D. (?) aurita {Vorticella Canicula, M.). 

 — Cylindrical, slender ; front straightly 

 truncated, auricled ; foot suddenly con- 

 stricted, toes small. The tremidous organ 

 obsen'ed by Corti was merely the vibra- 

 tile lining membrane of the anterior por- 

 tion of the alimentary canal. Amongst 

 ConfervEe. 1-160". 



D. catellina {Cercaria cateUina, Vorti- 

 cella Larva, M,). — Oblong, short, ends 

 ti'uncated ; foot short, and inferior. The 

 small size of this animalcule is unfavour- 

 able for observing its internal organiza- 

 tion. It is found at all seasons of the 

 year in open water, and in infusions 

 covered with a green pellicle, which is 

 often filled with its eggs; these; when 



rapidly developed by genial weather, 

 cause a milky turbidity in the water 

 1-360". 



D. conura. — Ovate-oblong, straightly 

 truncated in front, and gradually attenu- 

 ated to a conical foot. Amongst Oscilla- 

 torise. 1-144". 



D. capitata. — Oblong, conical, obliquely 

 truncated and dilated in front ; toes long, 

 without apparent base, or foot. Feeds 

 upon Chlamydomonas and Navicula. 

 1-300". 



D. caudata {Vorticella fur cata, M.). — 

 Elongated, conical, obliquely truncated 

 anteriorly, but not dilated ; foot distinct, 

 short ; toes long. In gi-een water. 1-200". 



D. (?) biraphis (Gosse). — Oblong, the 

 head and abdomen gently swelling ; toes 

 long, slender, straight, and perfectly 

 even in thickness ; eyes placed close to- 

 gether, frontally; jaws protrusile; alimen- 

 tary canal very large, projecting behind 

 and above the gizzard, always filled with 

 green matter. Length, including toes, 

 1-110". 



Genus TRIAETHRA (XXXIII. 406-408).— Eyes two, frontal; foot 

 simple, styliform ; breast-fins two. Beside the rotary organ, internal band- 

 like muscles are observed, and two bristles, or fins, which assist in leaping, 

 as in Polyartlira. The oesophageal bulb has two double-toothed jaws, as in 

 Rotifer ; the oesophagus is long in one species, short in the other ; alimentary 

 canal simple, conical or constricted, with two spherical glands. An ovary 

 and contractile vesicles are seen ; the eggs, when expelled, remain attached 

 by threads. The nervous system is indicated by the two red eyes, placed 

 upon ganglia. Both species often produce a milky, tiu-bid appearance in the 

 water, when developed in masses. A thii'd species is now added. 



when the animal is swimming ; 406 a side 

 (right) view of a full-grown specimen — 

 the styles are advanced, preparatory to 

 leaping.) Found with Hydatina senta 

 and Brachionus urceolaris. Length, with- 

 out cirrhi, 1-140". 



T. mystacina {Brachionus passus, M.). — 

 Eyes close together ; two anterior cirri, 

 or bristles ; foot nearly double the length 

 of the body; jaws very soft. 1-216". 

 In water-tulbs. 



T. breviseta (Gosse). — Cylindrical ; 

 pectoral and caudal spines each about 

 one-fifth of total length, and very slender. 

 Length, including foot, 1-185". Leaming- 

 ton. 



T. longiseta {Trichoda, M.).— Eyes 

 distant ; the cini or beards, and the foot, 

 are nearly three times the length of the 

 body. This species is distinguished from 

 the following one by the greater length 

 of cim ; by larger eyes, further removed 

 from each other ; by a distinct stomach, 

 with a constriction separating it from 

 the long portion of the alimentary canal ; 

 and, lastly, by its long oesophageal tube. 

 It is readily distinguished by its leaping 

 movement whilst swimming, (xxxiii. 

 408, a young animal emerging from the 

 e^^, the cirri or styles being, as yet, soft ; 

 407, back view of a young specimen — it 

 shows the gi'eat separation of the eyes and 

 the styles, in the position they occupy 



Genus RATTULUS (XXXIII. 409).— Eyes two, frontal; foot simple, 

 styHfonn ; no cim or beard. The organization at present discovered com- 

 prehends several undefined rotary muscles, an oesophageal head, mthout di- 

 stinct teeth or oesophageal tube, a simple conical alimentary canal, with two 

 round glands, an ovary, and the eyes. 



