68 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



Calcified sooecia. Calcification of the frontal in the Anasca and of the 

 apertura in the Ascophora is a phenomenon quite frequent and still inexpli- 

 cable. It is produced by the death of the polypide by accident or disease. Gen- 

 erally the calcined lamella is perforated; rarely it remains entire; sometimes it 

 disappears under the tremopores. 



We have mentioned the calcified zooecia each time that we have observed them, 

 but for want of material we have not been able to make a detailed study. Follow- 

 ing are some examples: 



Ramphonotus laevis, new species (pi. 1. fig. 14). 



L'tctonychoceHa lAlam< lltiritt. new species (pi. 33, fig. 3). 



Floridinella vicksburgica Canu and Bassler, 1917 (pi. 82, fig. 26). 



Metroperiella biplanata, new species (pi. 47. fig. 15). 



M etroperiella porosa, new species (pi. 47. fig. 8). 



Smittina exig:ia, new species (pi. 59, fig. 17). 



Smittina angulata Eeuss (pi. 60, fig. 8). 



Cyclicopora spongiopsis De Gregorio (pi. 88, -fig. 10). 



Porella irregularis, new species (pi. 62, fig. 20). 



Porella abdita, new species (pi. Co, fig. 3). 



Porella portentosa, new species (pi. 64, fig. 17). 



Adeonidae^ Hippopodinidae. 



Vrstibulnr arch. The superior portion of the tentacular sheath is called thft 

 vestibulum. The latter is calcified sometimes in the vicinity of the anter of the 

 apertura; this calcified lamella is the vestibular arch. It is very delicate and is 

 little resistant in fossilization. We have rarely found it on our American speci- 

 mens. (Figs. 15, C. D.) 



ZOAEIUM. 



Terminology. For a given species, the form of the zoarium is almost, always 

 identical; nevertheless it is not rare to find some species both incrusting and free, 

 the latter form of growth being only an advanced phase of the former. Some of 

 the genera of bryozoa, now entirely archaic, were based on growth forms alone, 

 and their names we now preserve in the literature simply in describing the form of 

 zoaria. Among such names are the following: 



Eschara refers to any free form of Ascophora with two lamellae back to back. 



Lunulites comprise all the free turbinate, conical forms. 



Lepralia, is an incrusting form. 



Biftustra has reference to a free form of the Anasca with two lamellae back 

 to back. 



Yincularia has rod-like zoaria. 



Celleporaria is a creeping form of the Anasca. 



Cellepora is any bryozoan made up of cumulate zooecia. 



1 1913. Larger (Ren6), La contre-gvolution ou dSggnerescence par I'herMite pathologique cause natu- 

 relle de 1'extinction des groupes animaux netuels pt fossiles. Essai de palopathologie gnrale compnrei'. 

 Paris. 



