32 BULLETIN 96, UNITED STATES NATIONAL MUSEUM. 



the zooecia frequently occurring in two forms, a and B^ and pro- 

 vided with a large operculum armed with teeth, which is suspended 

 by strong hinge-teeth; the polypide tube is never continued proxi- 

 mally beneath the cryptocyst cover. (After Levinsen, 1909.) 



Genotijye. — Steganoiwrella {Membranipora) magnilabris Hincks, 

 1880. 



Range. — Lutecian-Recent. 



Four well-marked new species have been discovered in the Jack- 

 sonian and Vicksburgian of the Southern States. 



Family THALAMOPORELLIDAE Levinsen, 1909. 



The tubifer zooecia have calcareous spicula in the shape of com- 

 passes and bows. The ovicells are hyperstomial, with two calcareous 

 layers, springing from the whole anter of the apertura; they are 

 closed by a horizontal cup-shaped chitinized operculum which is 

 connected at its base with the operculum of the gonozocecium. The 

 opesiulae are always completely separated from the apertura. The 

 opercular valve is membranous or chitinized, and more or less com- 

 pletely separated from the ectocyst by a single or double chitinous 

 sclerite. Interzooccial avicularia occur. 



Genus THALAMOPORELLA Hincks, 1887. 



1887. Thalamoporclla Hincks, Critical Notes ou the Polyzoa, Annals Maga- 

 zine Natural History (5), vol. 19, p. 104. 



Characters same as for the family. 



Genotype. — Thalamoporella (Flustra) rozieri Savigny-Audouin, 

 1812-1826. 

 Range. — Aquitanian-Recent. 

 A new species occurs at the top of the Vicksburgian in Mississippi. 



Division III. PSEUDOSTEGA Levinsen, 1909. 



There are no parietal muscles. The hydrostatic system is external ; 

 there is a special hypostege on each zooecium. 

 The families of this division are: 



Membranicellariidae Levinsen, 1909. 



Cellariidae Hincks, 1880. 



Coscinopleuridae Canu, 1913. 



Family CELLARIIDAE Hincks, 1880. 



The whole frontal wall of the zocecia is a cryptocyst and they have 

 a well chitinized, bilaminar, simple operculum with a straight or 

 concave proximal margin. Within the proximal and sometimes also 

 within the distal margin of the aperture is placed a pair of (or some- 



