during the Year 1828. 423 



•to 



Li, bilineata ; and the Z/. sepium, which takes the appearance 

 of the jL. arenicola. 



M. Milne Edwards has arrived at the same results as M. 

 Dugez with regard to indigenous species, but has invented a 

 new method of characterising all kinds, which is by the scaly 

 plates of the head. Their number, shape, and proportions are 

 generally constant in each species, and sufficiently different 

 from others to adopt this method. 



M. Dugez has also been observing the deglutition of rep- 

 tiles in general, and gives some new details on the changes 

 which take place in the tongues of frogs, &c., which are short 

 and immovable in the tadpole, but which in the frog, and es^ 

 pecially in the toad, become organs of extreme mobility. 

 When still, they are folded back towards the throat, but can 

 be unfolded with astonishing rapidity. The author describes 

 the muscles of this singular mechanism, and those which pro- 

 duce the darting and vibrating movements of the tongues of 

 adders. 



M, Dugez, professor at Montpelier, has composed a me- 

 moir on the respiration of that family of the Annelides which 

 is destitute of branchiae, as the fresh-water worm, the leech, 

 and the Nai'sa. The Naisa has a dorsal vessel, which makes 

 a fold at each ring of the body, and carries the blood from 

 behind to before ; and a ventral vessel, less in size, and less 

 flexible, which conveys it in a contrary direction. These two 

 communicate by anastomoses, and on each side is a contractile 

 bladder, which appears to receive the blood of the dorsal ves- 

 sel, and, as it contracts, to send the blood into the ventral. 

 The network of anastomoses in the tail, which is constantly in 

 motion, forms a very complicated vascular apparatus, which 

 appears to M. Dugez to be the organ of respiration. Leeches 

 have a dorsal, a ventral, and two large lateral vessels, all of 

 which communicate in different manners. As to their respir- 

 ation, besides that which is effected by the skin, another way 

 exists by means of a number of bladders, placed on each side, 

 and communicating with the exterior by a small pore. The 

 same author makes a number of other valuable observations 

 on the circulation of the blood, and the generation of these 

 animals, and proves that the iumbricus is not viviparous, as 

 generally supposed ; and that which has been taken for a foetus, 

 is nothing but an intestinal worm. In another memoir the 

 author treats of a genus but little known, called by naturahsts 

 Planaria ; the body is flat and thin, and of a parenchymatous 

 substance. The author forms these animals into a family, 

 which he names Planarise, which family he divides into several 

 genera. Although very quick in their movements, they are so 



