Invertebrate Animals of the IVestern Cuast of France. 33 



Dujai'dinia, are furuished with bristles as in the other Annchda 

 Errantia ; but the- e are merely passive weapons of defence, since 

 they remain perfectly immoveable. Sometimes the animal changes 

 its position in the water by agitating its tail briskly like a long 

 oar, but in general it swims slowly by means of the abo^■e-men- 

 tioned lateral palettes, which consist of cilia circularly arranged 

 upon the edges of cup-shaped cavities, supported l)y papillae placed 

 upon the sides of the body and between the feet. In the form of 

 its digestive tube and the large size of its ova, Dujardinia also 

 approximates the Rotifera. 



Some further details are of interest from tending to indicate 

 the links whereby the Annelida are connected to the Planaria 

 and Entozoa. Thus the Nemert^e agree with the Annelida in the 

 general arrangement of their vascular system, but resemble much 

 the Hiriidines in the structm'e of their buccal apparatus and 

 many other points of internal organization, while their reproduc- 

 tive organs are analogous to those of many Entozoa ; their ner- 

 vous system may be compared to that of the Lingidte, and their 

 digestive tube, in place of extending the whole length of the body 

 and opening posteriorly by an anal oritice, as in all the typical 

 Annelida, terminates towards the anterior third of the body in 

 a cul-de-sac which communicates externally by the mouth alone, 

 as in some of the lower organized Entozoa and most Zoophyta. 



The very singular observations made by INI. Quatrefages upon 

 the propagation of the genus Syllis have already been given in a 

 previous number of this Journal. It remains only for us to add, 

 in respect to the Annelida, that in a lai'ge number of the Annelida 

 Errantia Jand TuUcola, and also in the Thalassemce and Nemertce, 

 which establish the passage between the ordinary Annelida and 

 Entozoa, he has recognised the existence of distinct male and female 

 individuals, has observed the formation of the spermatozoa in the 

 Nemertce, and by his remarks upon the development of the ova 

 in the Terebellce, has extended to the class Annelida the import- 

 ant fact determined by Herold, llathke, and other embryologists, 

 respecting the relation of the vitellus to the dorsal surface of the 

 embryo in Insects, Arachnida and Crustacea. 



Lastly, M. Quatrefages, in examining the mechanism of motion 

 in the polj^s of the genus Edivardsia, has arrived at the same 

 conclusions with i\Ir. Bowman relative to the theory of muscular 

 contraction ; for he has observed that the fibres of one and the 

 same muscle do not all act simultaneously, but that those which 

 contract, drawing along mth them the adjacent fibres in a state 

 of repose, give rise to the zigzag folds which have been considered 

 as the efficient cause of the shortening of the muscle. 



Touching the subject of animal phosphorescence, our author has 

 been led, from the microscopic study of the small transparent 



Ann. ^ Mag. N. Hist. Vol. xiv. D 



