ANNULATA. 221 
belongs probably to the nervous system. In some species with 
straight intestinal canal, there have been observed at the sides two 
tortuous canals running longitudinally, which, without giving off 
lateral branches, bend round in a loop at the back part. Respira- 
tion is probably effected by the skin itself, and the water on the 
surface is constantly renewed by the vibratory motion. 
As nervous system in many a double nervous ganglion has been 
observed, which lies at the anterior end, and from which many 
branches arise. The eyes, which are in some instances very nume- 
rous, present in many a transparent body, corpus vitrewm or lens 
erystallina. 
The reproductive power is very great, and severed parts grow, as 
appears from the observations especially of Dues and J. R. Jonnson, 
to new animals. In some propagation occurs by spontaneous division. 
The sexual organs have one common or two separate openings behind 
the mouth; in the latter case the anterior opening belongs to the 
male organs of copulation. Two long tubes supply the office of 
testes, and end as vasa deferentia in a seminal vesicle, with which a 
penis of various form is connected. The spermatozoa have been 
observed by QUATREFAGES and Von Sresotp. <A double oviduct 
leads to a spacious vagina, into which two special hollow bodies also 
open. The eggs lie dispersed in the parenchyme of the body, 
between the cecal branches of the intestinal canal (QUATREFAGES), 
where probably they are contained in special ramified tubes 
(ovaries). 
Compare on this family : 
Von Barr, Ueber Planarien. Nov. Act. Acad. Ces. L. C. nat. 
cur. Vol. x1. P. 2, pp. 690—730. 
Ducss, Recherches sur Torganisat. et les mewrs des Planariées, 
Ann. des Se. nat. xv. 1828, pp. 139—187 ; Observations now. sur 
les Planaires, ibid. xx1. 1830, pp. 72—92. 
A. 8. Orrstep, Lntwurf einer systematischen Eintheilung und 
speciellen Berschreibung der Plattwiirmer. Mit Holtz-schnitten und 
3 Tafeln. Copenhagen, 1844, 8vo. 
A. De Quatreraces, Mémoire sur quelques Planariées marines, 
Ann. des Sc. nat. 3me Série, Tom. iv. 1845, Zoolog. pp. 129—184. 
Pl. 3—8. 
M. 8. Scuutrzn, Beitriige sux Naturgeschichte der Turbellarien. 
Erste abtheilung. Mit Kupfertaf. Greifswald, 1851, 4to. also in 
WiecMmann’s Archiv. 1849. § 290. 
