NORTH AMERICAN EARLY TERTIARY BRYOZOA. 231 



Rosseliana with clearly marked and constant opesiules. Membranipora ociiralix 

 Seguenza 1879 is classed in this genus. 



Genus DACRYONELLA Canu and Bassler, 1917. 



1017. Dacriionclla CANU and BASSLER, Synopsis of American Early Tertiary Cheilostome 

 Bryozoa, Bulletin 96, United States National Museum, p. 28. 



The polypidian convexity protrudes very little and is inconstant. The 

 opesiules are large, round, lateral indentations. The ovicell is endozooecial. There 

 are no opesial processes (therefore an opercular valve) . The opesium is elongated 

 (therefore the parietal muscles are much developed). The avicularia are very 

 small, constant, placed in all the interzooecial angles, and have the form of small 

 tear drops. 



Genotype.- Dacryonella octonaria Canu and Bassler, 1917. Jacksonian. 



This is a Rosseliana ornamented with avicularia. As in this genus also, the 

 opesiules are inconstant and placed very far from the aperture in consequence of 

 the great development of the parietal muscles. 



DACRYONELLA OCTONARIA Canu and Bassler, 1917. 



Plate 36, figs. 9-20. 



1917. Dacryonella octonaria CANU and BASSLEK, Synopsis of American Early Tertiary 

 Cheilostome Bryozoa, Bulletin 96, United States National Museum, p. 28, pi. 3, fig. 4. 



Description. The zoarium incrusts small shells or more often creeps over 

 algae; very frequently it consists of many superposed lamellae. The zooecia are 

 somewhat elongated, confluent among themselves, vaguely polygonal; the mural 

 rim is broad, especially below, flat, smooth, oblique. The cryptocyst is terminated 

 distally in a small polypidian convexity. The avicularia are straight, interopesial, 

 triangular, projecting chiefly at the point. 



. (A0=0.10mm. 

 Measurements. Opesia ot large zooecia^, _n-M 



Large zooecia (Lz= 0.40 mm. 



\lz 0.30-0.40 mm. 

 Opesia of fAo=0.18mm. 

 small zooecia 1 70=0.10 mm. 



. fs=0.40mm. 

 Small zooecia 4 , 



U;?=0.30 mm. 



Variations and affinities. The polymorphism of this species is very remarkable. 

 On the same zoarium. without apparent reason, the zooecia are considerably in- 

 creased in size, chiefly at the extremity of the fronds. The larger zooecia are 

 always grouped together, none of them being isolated; then their opesium becomes 

 transverse and almost triangular. 



The polypidian convexity is here symmetrical, but as usual is not constant. 

 However the proximal border of the opesium is nearly always straight or convex 

 and very rarely concave. We know that this phenomenon may be observed in 

 other genera of different families and that it can not serve as a generic character. 



