OF THE HYDATIX^A. 



689 



This genus (Battidus, or Ratulus) was established by Lamarck ; but the 

 animals included in it by him were referred by Ehrenberg to two genera, 

 Mastigocerca and Jibnoc^rca, and the term Rattulus conferred upon an animal 

 placed among Cercariae, and called by Miiller Tr'ichoda Junaris. '^ The Mas- 

 tigocerca caiinata (Ehr.)," observ^es Dujardin, " is described as loricated, and 

 enters into the family Euchlanidota ; and Monocerca Rattus, without lorica, is 

 placed among the Hydatinoea; but the beings described under these two 

 appellations represent but a single species, Ratulus .... The Monocerca 

 bicornis of Ehi^enberg would seem to be a distinct species, by reason of the 

 horns with which it is armed in front." 



Rattulus lunaris (Trichoda lunar is, 

 M.). — Small ; eyes remote from the 

 frontal margin ; foot decurved, lunate. 

 No teeth are seen (xxxiii. group 409). 



In turfy pools. 1-288" 

 R. carinatus (Duj.) 

 Monocerca Rattus. 



(xxx-^^ii. 22); 



Oenus DISTEMMA. — Eyes two, cer^•ical ; foot forked ; ix)tary organ com- 

 poimd. The oesophageal head supports, in three species, jaws, with two teeth 

 each ; in one sp*3cies with more than two ; oesophag-us short ; aUmentary 

 canal simple, conical, with two spherical glands. An ovary, and in D. (?) 

 marinum glands and a contractile vesicle are seen. No satisfactory details 

 of a water-vascular system are ascertained ; the eyes are red, except in one 

 species, in which they are colouiiess, and in all, except D. marinum, they are 

 situated behind the head of the oesophagus ; in that one they are anterior, 

 but below the rotary organ. The eggs are never attached to the parent, nor 

 are they developed in large masses. 



DiSTEMiviA Forjicula. — Cylindrico- 

 conical ; eyes red ; toes thick, recurved 

 and. dentate at the base. The eyes are 

 placed at the end of a long cylindrical 

 nervous ganglion ; the rotary organ con- 

 sists of four parts, xxxiii. 411 is a side 

 (left) view, and fig. 410 shows the jaws 

 extended for seizing prey. Perty be- 

 lieves this to be identical with Fnrcu- 

 iaria Forjicula, ha^^ng but a single eye. 

 1-120". 



D. setigerum. — Ovato-oblong ; eyes 



red ; toes setaceous and decurved. 

 1-216". 



D. (?) marinum. — Ovato-conical ; eyes 

 red, close together ; foot long ; toes thick, 

 the length of the foot ; jaws many- 

 toothed. In sea-water. 1-144". 



D. (?) forcipatum. — Ovato-oblong ; 

 eyes colourless ; foot short, with stout 

 toes. If the two colourless vesicles are 

 not eyes, it must be placed in the genus 

 Pleurotrocha. 1-288". 



Genus TRIOPHTHALMUS (XXXIII. 412-414).— Eyes three, cervical, 

 sessile, in a row ; foot forked ; rotaiy organ compound. It has a large oeso- 

 phageal head, with two (single-toothed ?) jaws, a long thin oesophagus, a 

 globose stomach-like protuberance, with two oval glands, and a thin intes- 

 tine ; two muscles move the foot. Several small tags seen in T. dorscdis. 



Teiophthalmus dorsalis. — Body cry- 

 stalline, turgid ; central eye largest ; foot 

 suddenly attenuated, its length half that 



of the body. This species, in form, re- 

 sembles Notommata ansata, but in size 



N. Mijrmeleo, (xxxiii. 412, dorsal side of 

 an animalcule extended as it appears 

 when swimming and vibrating ; fig. 413 

 one in the act of unfolding itself, and 

 fig. 414 another contracted.) 1-40". 



Genus EOSPHORA (XXXIII. 415). — Eyes, according to Ehrenberg, 

 sessile, three — two frontal, one cervical ; foot forked. The rotary organ is 

 composed of numerous muscular portions. An oesophageal head, provided 

 with two single -toothed jaws, a short oesophagus, a simple conical alimentary 

 canal, Tvdth two ovate glands anteriorly, an ovary, somewhat extended, and 

 a contractile vesicle, are also discoverable. Transverse bands are observable 



2y 



