NORTH AMERICAN EARLY TERTIARY BRYOZOA. 67 



example, in which the zooecial cells are relatively very elongate, the tentacles are 

 short and never exceed a third of the length of the bryozooid. Finally they are 

 of a medium length in other species and have about two-fifths of the length of the 

 bryozooid. The dimensions in thickness are also quite variable. Yet it seems that 

 they are proportional to the dimensions of the general cavity and inversely to 

 the number of the tentacles." (Translated from Calvet, 1900.) 1 



We give for each species the exterior micrometric dimensions of the zooecia ; our 

 measurements only express the average or the most frequent measurements. We 

 are not able to draw up any general law. Very frequently the length is double the 

 width; the other relations are more rare. There must be some very interesting 

 studies to be made along this line, but we have not had th& time to do so. and, more- 

 over, a zoological basis is wanting absolutely. 



Total regeneration. The regeneration of the polypide is a phenomenon well 

 known in bryozoology ; it leaves no trace in the Cheilostomata. Sometimes, for causes 

 unknown, it is the entire individual which is regenerated. This total regeneration 

 leaves some external traces. It was thoroughly studied by Levinsen in 1907, 2 and 

 he cited numerous examples. In the course of our work we have noted some inter- 

 esting observations which confirm those of Levinsen. Following are some of the 

 cases : 



1. Replacement of a zooecium by an avicularium. 



Hincksina Tnegavicularia, new species (pi. 23, fig. 1). 

 Lacerna hexagonalis, new species (pi. 44, fig. 20). 



2. Female polypide succeeding a male polypide. 



Hincksina elegans, new species (pi. 80, fig. 15). 



3. Female zooecium inverted and succeeding a male polypide. 



Membraniporidra laticella, new species (pi. 26, fig. 5). 



4. Replacement of a zooecium by a zooecium. 



FloridineUa vicksl irgica, Canu and Bassler (pi. 82, fig. 26). 



5. Replacement of an ordinary zooecium by an inverted zooecium. 



Membraniporidra laticella, new species (pi. 26, fig. 4). 



6. Replacement of a normal zooecium by a calcified zooecium. 



Euritina tecta, new species (pi. 5, fig. 2). 

 Velumetta plicata, new species (pi. 34, fig. 4). 



7. Replacement of an avicularian zooecium by another avicularian zooecium. 



Schizomavella granulosa, new species (pi. 46, fig. 15). 

 3. Triple regeneration. 



GrammeUa crassimarginata Hincks (pi. 24, fig. 13). 



Alderina crassa, new species (pi. 29, fig. 7). 

 The effecting cause of fotal regeneration is unknown. 



1 Contributions a 1'historie naturelle des Bryozoaires ectoproctes marius, Travaux d'Institut de 

 Zoologie de 1'Universitg de Montpelier, Memoire No. 8, p. 183. 



- 1907. Levinsen. Sur la rtge'ne'ration totale des Bryozoaires, Bulletin Academic Royal des sciences et 

 des Icttres de Danemark, pp. 151-160. 



