Zoological Collections. Invertebrata. 



iorgans analogous to those of the Planaria, viz. a large penis, and an uterus, 

 with two long oviducts, containing ovula and ova already formed. In 2). 

 grossum, he observed the laying of the ova, which are attached to submerged 

 vegetables by a mucous exudation ; and he saw individuals in the act of 

 copulation, which is effected as in the Planarice. The genital pore or point 

 of communication between the two individuals during the coitus, is placed 

 immediately behind the mouth. 



With regard to the Planarice, M. Dug^s first observes, that Planaria 

 fusca is identical with PI. torva. He insists on the necessity of adopting a 

 constant datum in the determination of the form of the body of these very 

 soft and contractile animals, and he advises that they should be always 

 examined when in motion, as at that time alone is their form regular and 

 constant. The new species which he describes are: — 1st, PI. vitta, common 

 in spring, in the brooks around Montpellier ; 2d, PI. cceca, a single indivi- 

 dual of which has been found in a brook almost dry; 3d, PI. longiceps, in 

 salt ponds, on the Ulva intestinalis ; 4th, PI. gonocepkala, in brooks of pure 

 water ; and, 5th, PI. viganensis, in springs of very pure water. 



A very remarkable disposition, which M. Duges has discovered in the 

 Planarice, is a wide and easy communication between the circulating system 

 and the genital apparatus. In several species he has seen the lateral vessels 

 surrounded, in a considerable portion of their extent, with whitish vesicles 

 forming a long bunch : and he has found that these vesicles are provided 

 with a neck, opening into the lateral vessel. " Are not these," asks M. 

 Duges, " true ovaria analogous to those of the Prostomata, and to which the 

 blood-vessels serve as oviducts ?" He has dissected copulating individuals 

 of the brown species, and has thus confirmed the double simultaneous intro- 

 mission, and the great elongation of which the penis is susceptible. He has 

 seen copulation take place in the same way in the PI. lactea, and has exa^ 

 mined the laying of the latter, and of the PI. nigra. Their reddish rounded 

 ova are not supported on a pedicle, like those of the brown species, but are 

 glued immediately on the walls of the vessel in Avhich the animals are kept. 

 He could thus discover, (at least with regard to PI lactea,) generally five to 

 six foetus, represented at first by an elongated vessel, and containing a pulpy 

 matter. At their birth, (li line long,) there could be seen in them a trunk, 

 a gastric apparatus, lateral vessels, but no trace of genital organs. Some- 

 times two foetus contract adhesions, and form synadelphous monsters 



Ann. des Sci. Nat. xxi. 72. 



Digestive Canal of the Infusoria This canal, in the Hydatina senta, pre- 

 sents, at its commencement, a globular pharynx of a muscular nature, which 

 is provided with two jaws, and which opens anteriorly in the mouth, in the 

 middle of the wheels, a little nearer the ventral aspect than the dorsal. Each 

 jaw is provided with six slender teeth, which are bifid. Posteriorly, the 

 pharynx gives origin to a short and narrow oesophagus, which, without being 

 dilated into a stomach, is continued immediately into the intestine. The 

 intestine is very thick, and contracts sensibly towards the posterior extre- 

 mity ; it terminates along with the oviduct in a common cloaca. The 

 opening of this cloaca is on the back of the animal, immediately above the 

 eighth pair of vessels. In the Zygotrocha nudas the intestinal canal is 

 thinner and turned spirally ; the cloaca is very extensible, and allows of the 

 accumulation of the execrements. At the commencement of the digestive 

 canal of all these animalcules, there are seen two small bodies, considered by 

 M. Ehrenberg as analogous to the pancreas. — Isis. 



