122 Bibliographical Notices. 



male and female organ in all adult individuals. The products of 

 both organs — spermatozoa and eggs — on their becoming detached, 

 are intermingled in the peri- intestinal cavity, where probably the 

 latter are impregnated. The testicle is situated at the extremity of 

 the stomach, in the place v^rhere we observe the ovary in other 

 genera : it appears when the polype approaches to maturity, is un- 

 equally pitted, and has very much the aspect of the ovary of birds 

 when they are not in season. 



The female organ or ovary is formed on the inner surface of the 

 fold of skin that lines the cell, and on one side near the mouth of 

 the sac. It is at first a mere tubercle, similar to an abnormal ex- 

 crescence, but it grows rapidly, and ova, in different stages of 

 development, are soon visible in it. In the young ova the vesicles 

 of Wagner and of Purkinje are distinctly seen. In those more ma- 

 ture they have disappeared, and we then discover an external vitel- 

 line membrane or chorion, and a vitellus underneath. The ovum 

 at maturity tears its envelope and falls into the peri- intestinal cavity. 

 From this it escapes into the sea by a distinct opening which is 

 formed at the base of the tentacula. On its exclusion the surface 

 does not appear to be covered with vibratile cilia ; and Van Beneden 

 was unsuccessful in tracing its further evolution. 



The increase of the polypidom from the development of buds is 

 next described. Van Beneden first remarks, that although this 

 polype is an animal of considerable complexity in its organization, 

 yet we here observe that it can be formed without the vesicle of 

 Wagner or of Purkinje, whence it is evident that these vesicles are 

 not indispensable to the formation of an animal, and they are to be 

 looked upon only as a means of isolation for the future individual. 

 Next the author inquires if all the textures of these inferior entities 

 proceed from cellules, agreeably to the doctrine of Schwann, and 

 he answers in the affirmative, although it is admitted that there are 

 diflferences between the cellules in them and in those of the superior 

 animals. After this. Van Beneden proceeds to trace the growth of 

 the bud, and the successive evolution of the organs of the polype, 

 which is done in a very clear and masterly manner. 



The characters of the genus and of its species are next given. 

 The L. repens is exceedingly abundant and common at Ostend. 

 The Laguncula elongata, a new species, is of less frequent occurrence : 

 it is distinguished by having an elongated pedicle which in general 

 exceeds the length of the cell, and the polype has 16 tentacula. 



We reserve the second memoir for a separate notice, for we should 

 not like to review in a more cursory manner our author's much- 

 prized labours. There are none on which we set a higher value. 

 In the meantime we have only to remark, that, in some preliminary 

 observations. Van Beneden expresses his opinion that the Linnsean 

 division of the animal kingdom will be found, after all, superior to 

 that of Cuvier or of Blainville, and more in harmony with the deve- 

 lopment of structure . In the first four classes the vitellus is absorbed 

 by the belly : these are the vertebrated animals that may be more 

 appropriately called the Hypovitelliens, or still better the Hypocoty- 



