ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 193 



appears at tbe spot where the last residue of the gastrula-mouth had 

 closed up. These statements are certainly in contradiction to those 

 of some other aiithors, but show that a common mode of development 

 may be set up, at least for the Gasteropoda. 



The second part treats of the structure of the velum, the origin of 

 the upper oesophageal ganglion, the structure of the primitive kidneys 

 and the intestine, and of the development of the persistent kidneys. 

 The author finds that the velum in Byiliinia is composed of large 

 cells containing vacuoles, and differs in some other characters 

 from the corresponding organ of other Gasteropod embryos; that 

 the superior oesophageal ganglion originates in the form of a 

 thickening of the outer germ - lamella (vertical plate) ; that the 

 primitive kidneys are composed of a few, not very large, perforated 

 cells; that the foundation of the persistent kidneys stands in no 

 genetic relation to the ectoderm ; and, finally, that in some respects 

 the intestine possesses interesting peculiarities. The author has 

 endeavoured to bring these results into agreement with his previous 

 statements upon the development of Planorhis, and to show that the 

 same laws which had proved to prevail in the case of Planorhis apply 

 also to Bythinia, and that the differences result from the greater 

 abundance of nutritive vitellus which is presented by the germs of the 

 latter. 



Norwegian Buccinidse.* — H. Friele describes the Buccinidse of 

 the Norwegian Arctic Expedition, which may be said to be especially 

 at home in the arctic and northern seas of both hemispheres. 

 According to the views of the author, this family comprises the 

 genera Jumala with one species, Volutopsis with one species, Pyrolo- 

 fusus with one species, Neptunea (t-ecte Nejptunia seu potius Neptunina) 

 with seventeen species, Troschelia with one species, and Buccinum 

 with twelve species ; in all six genera and thirty-three species. The 

 varieties of other species are also noticed. Ten species are for the 

 first time described and figured. It may be doubted whether the 

 grounds of distinction between these genera are sufficient, and 

 whether they are not all merely sections of the Lamarckian genus 

 Fusus and the restricted genus Buccinum. The author attaches con- 

 siderable importance to the dentition as a generic character ; but this 

 is, at any rate, a difficult basis of classification. What are we to do 

 with the fossil, and consequently now toothless, Gastropods? The 

 structure, and even the presence of the odontophore, in that order of 

 MoUusca depends on the nature of their food. Herr Friele has con- 

 clusively proved that in the Buccinidse " diversity of dentition affords 

 anything but a trustworthy guide " in distinguishing species. One 

 important character of such distinction has not been lost sight of by 

 him, viz. the shape of the apex or embryonic whorls. 



Sinisigera.f — A. E. Craven, who has published a monograph on 

 this genus, now states that he has been satisfied as to the shells of 



* 'Den Norske nord-havs-espedition, 1876-8. VIII. Zoologi, Mnllusca* 

 1. Buccinidse.' 6 pis. and map. 4to, Christiania, 1882. Cf. Ann. and Mag. Nat- 

 Hist., xi. (1883) pp. 216-9. 



t Ann. and Mag. Nat. Hist., xi. (1883) pp. 141-2. 

 Ser. 2.— Vol. III. O 



