S04 NdTES AND MEMORANDA. 



geneous protoplasm, Salensky describes the principal internal 

 organs {vestihUe, asophagus, stomach, rectum) as formed by 

 successive modidcations of an elongate cavity hollowed out in 

 the solid, central mass of endodermal cells. According to Vogt 

 the vestibule has its origin in a small empty space, present from 

 the first in the midst of the protoplasmic contents of the bud. 

 The other organs are formed by " the differentiation of an undi- 

 vided sarcodic mass." The stomach is, in the first instance, a large 

 ovoid body ( accumulation of protoplasm), placed transversely 

 below the primitive cavity, which is subsequently hollowed out in 

 the centre, and ultimately brought into communication with the 

 cavities of the oesophagus and intestine. These are not unim- 

 portant differences. Must we suppose that such diverse plans 

 of development occur amongst the species of the same natural 

 group ? Or are we to believe that there must be errors of 

 observation on one side or the other? 



Our author proceeds to give an account of the gemmation of 

 Pedicellina, which he finds to be strictly analogous to that of 

 Loxosoma. I do not propose to follow him trough this portion 

 of his paper, but may remark that his detailed description of the 

 development of the internal organs runs parallel at almost all 

 points to that which he has given us of the same process in 

 Loxosoma} 



General deductions. The author fully accepts the group 

 of the Entoprocta as constituted by !Nitsche. 



In opposition to the views of the latter author, who considers 

 that the polypide of Loxosoma is homologous with the polypide 

 onli/ (apart from the zoooecium) of the Ectoprocta, and that in this 

 form there are no parts homologous with the zoooecium or cell, 

 Salensky holds that the ectoderm of Loxosoma corresponds to the 

 zoooecium of the Ectoprocta ; its digestive canal and tentacles to 

 the digestive canal and tentacles of the polypide of the Ectoprocta; 

 its parenchyma and muscles to the mesoderm and muscles of the 

 Ectoprocta. He bases his view on a careful comparison of the 

 gemmation of the two groups. In the Ectoprocta and the 

 Entoprocta we may always recognise, he holds, the same parts, 

 the zoooecium and the polypide, which together compose, in one 

 case, the mc'tamere {i.e. zooceciutn -cum-jioli/pide) of the colony 

 of the colonial Bryozoa; in another, an independent individual 

 such as Loxosoma. 



The distinctive generic characters of Loxosoma the author 

 considers to be the absence of the diaphragm separating the 



' This certainly affords a strong presumption in favour of the accuracy of 

 his observations in the latter case. 



