16 



Crisia, and in Cr. ramosa Harmer he has found it partially separated from the rest 

 of the cavity by a calcareous valve which however is not developed on the frontal 

 wall. I have found a similar valve in Cr. hamifera^) n. sp., but in Cr. ebiirnea, 

 (pi. VII, figs. 11, 12) Cr. denticiilaia and Cr. aculeata it is replaced by a similar 

 continuous ring as that found in the ooecia of Meliceritites. It is provided with more 

 or less finely ramose processes the character of which is distinctly diilerent in the 

 three species. 



The Regeneration. 



Besides the regeneration of the polypide which is no doubt a common feature 

 in all Brijozoa a regeneration of the whole individual has been shown to lake place"') 

 in a number of species both in the Ctenostomata and the Cheilostomata, and such 

 a regeneration I have also found in most species of the present division. While 

 in the Ctenostomata this regeneration takes place in that manner that the old indi- 

 vidual drops olT. and a new one takes its place, in all species the zooecium of 

 which is more or less calcified the new individual develops within the old zooecium, 

 and that such a complete regeneration has taken place is evident from the fact 

 that a new aperture is seen within the old one. In the Cheilostomata I have shown 

 that this regeneration takes place in such a manner that the different forms of 

 bryozoids may replace each other, and the same case I have found also in the Meli- 

 ceriliticlae. The regeneration in this division has hitherto been overlooked or inter" 

 preted as a certain form of closure, f. insl. by Gregory who in Mel. durobrivensis 

 speaks about a closure by means of an inverted funnel-shaped cap pierced by a 

 pore. Here we have to do with a regeneration of a new heterozooecium within 

 an old zooecium. As I am later to give information of the regeneration in the 

 single species described I shall here only give a short summary of the main features 

 of this process. 



In the Melicerititidae as in the Cheilostomata we can discern between the fol- 

 lowing four forms: ') the regeneration of a new zooecium within an old one (pi. 

 Ill, figs. 2, 7; pi. IV, figs. 4, 8, 11,14; pi. V, figs. 2, 4, 19; pi. I, figs. 3, 4, 16); -) the 

 regeneration of a new zooecium within a heterozooecium (pi. II, figs. 5, 7, 12; pi. 

 V, fig. 14); ") the regeneration of a new heterozooecium within an old one (pi. I, 

 fig. 4; pi. II, figs. 6, 9, 20, 22; pi. Ill, figs. 6, 7; pi. V, fig. 15) and ') the regeneration 

 of a new heterozooecium within an old zooecium, which is perhaps the most com- 

 mon form of regeneration (pi. I, figs. 18, 19; pi. Ill, figs. 1, 3, 4, 5, 27; pi. IV, figs. 3, 

 7, 10, 14). When a new large heterozooecium is regenerated within an old one it 

 may fill the old aperture completely (pi. II, figs. 20, 22) or only a part of it, and 

 in the latter case the space between the two apertures is gradually filled by a clo- 



') This species whicli is talcen at lat. 33^ i) N., long. 129° 18 W. is in the dorsal surface provided 

 with a number of hook shaped appendages eacli of wliich through a corneous joint is fixed to the 

 proximal part of an iuternode. -) 17. 



