EXPLANATION OF PLATES 



Unless otherwise indicated, all the specimens are magnified X 20, 

 and are from the Vincentown marl, Vincentown, N.J. 



Plate 1 



Figure 1. Vincularia acutirostris, new species (p. 13). 



The free vincularform zoarium, showing that the avicularia are 

 iuterzooecial, lozenge-shaped, and in longitudinal rows. 

 2,3. Membranipora nellioides, new species (p. 13). 



2, A segment terminated by a regenerated cell. 



3, Base of a segment with the avicularia intact. 

 4-7. Aplousina contumax, new species (p. 14). 



4, Portion of the encrusting zoarium, showing several regenerated 

 zooecia. From near Blackwoodstown, N.J. 



5, An ovicelled colony, illustrating also the formation of the distal 

 zooecium and the distal septula. The ovicell is very small and 

 endozooecial. From near Blackwoodstown, N.J. 



6, Ancestrular zooecia deformed by an irregularity of the sub- 

 stratum. 



7, Complete zoarium, showing the ancestrula with cryptocyst, some 

 regenerated zooecia, the thin basal pellicle, and the orifice of the 

 large distal septula. 



8. EUisinidra Keteropora Gabb and Horn, 1S62 (p. 19). 



Encrusting ovicelled specimen, showing the structure of the hyper- 

 stomial ovicell and several calcified zooecia. 



Plate 2 



Figures 1-6. Aplousina disjtincta- Gabb and Horn, 1862 (p. 15). 



1, Surface of the bilamellar zoarium with several ovicelled 

 zooecia. 



2, Surface in which incomplete calcification occasioned the total 

 disjunction of several zooecial series. 



3, Zooecia showing partial disjunction. One cell is regenerated. 



4, Surface with regenerated zooecia, which are here primoserial. 



5, Lateral face of the zooecia, illustrating the bilamellar 

 zoarium and showing the uniporous septules. 



6, Dorsal side of a free lamella, showing the zooecial dis- 

 junction. 



7,8. Granosina altimuralis Ulrich and Bassler, 1907 (p. 17). 



7, Ancestrular zooecia of the encrusting zoarium. Here there 

 is a double ancestrula. 



8, Regular zooecia of an ovicelled zoarium. The endozooecial 

 ovicell and the small oblique triangular avicularium are 

 9hown. 



Plate 3 



Figures 1,2. M> mbraniporidra pcrampla Gabb and Horn, 1S62 (p. 18). 



1, Portion of the encrusting zoarium, showing four regenerated 

 zooecia and a giant regenerated one. 



2, Portion of an ovicelled zoarium. The ovicell is hyperstomial, 

 smooth, and buried in the distal zooecium. 



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