3in 



seen in the wliole colony seem to be in nuilual connection witli each other, often 

 l)y means of a narrow, tube-shaped prolongation, and through one or several of 

 these they seem as a rule to open out on the surface of the zocccia. 



hi the above-cited work Whitelegge puts forward the extremely peculiar 

 view, that in these forms in contrast to what is known in all other calcilicd 

 Brijozod the new zooccia arise scattered amongst the fully developed and that the 

 chambers which are here called lunoecia are just such rudiments of new zoax'ia, 

 which according to the author may arise both in the oldest and youngest [)ails 

 of the colony. This view is however quite incorrect and is in complete conllict 

 with my investigations on these chambers. Further, it is readily seen that the 

 new zonecia in all members of this family are formed at the free margin, and 

 even the idea that new zooecia can be intercalated between the older in a well- 

 calcified Bryozoa colony is so improbable that I have no hesitation in declaring 

 such a process impossible. The improbability is further increased in that a nnmbei- 

 of these species have a very regular form, which is conditioned just by a regular 

 mode of growth. Mac Gillivray' does not hesitate to accept ^\'h i telegge's sup- 

 position, but with the modification that new zoo'cia according to him arise also 

 between the marginal zoo-cia. In the species of the genus Coneschdrelliiut at the same 

 time as new zoa'cia arise on the margin of the colony, the inner cavity gradually be- 

 comes filled with small avicularia, which stand in connection with the zocrcia and 

 with each other by means of small uniporous rosette-plates, and a longitudinal section 

 through such a colony shows them to be arranged in horizontal layers. The small 

 pore situated immediately distally to the aperture and which according to White- 

 legge is covered externally by a membrane, leads into a small cavity in the wall 

 of the zocrcium, which sometimes projects on the inner surface. The ooecia, which 

 have hitherto only been found in ConeschurcUinii phUippensis and C. cancellata 

 (PI. XXIII, figs. .S a, S b), occur in the latter species in very small numbers and 

 usually in the neighl)ourhood of the free margin of the colony. Their outer aper- 

 ture leads into a space formed by the peristome, at the bottom of which is the 

 zooecial operculum. 



The rule in this familj^ that all the other separating walls are single holds 

 true also for those sejjarating the zoci'cia in the two ojjjiosite layers in two-layered 

 colonies. In these further the zoa-cia of the one layer extend in between those of 

 the opposite layer in such a manner, that a section through the thickness of the 

 colony shows the zoa>cia in the two layers to be separated by a zigzag line. 



How far the division of the genera |)roj)ose<l here is natural must be deter- 

 mined by investigation of a larger material. 



' 76, p. 88. 



