NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 



141 



Measurements. — Apertura., „',' 



^ lia =0.10 mm. 



Zooecia 



Zz = 0.40 mm. 



Uz =0.20-0.30 mm. 



Affinities. — This species is very easy to recognize by its intcrareolar radiating 

 costules; however, this character is much less apparent on the zooecial margins 

 where the pleurocystal calcification is incomplete. 



Occurrence. — Pliocene (Caloosahatchee marl) : Shell Creek, De Soto County, 

 Florida (very rare) . 



Holotype.— Cut. No. 68634, U.S.N.M. 



Family EURYSTOMELLIDAE Levinsen, 1909. 



Levinsen's original description is as follows: 

 No spines. The thick-walled and strongly calcified zooecia lack a covering membrane and have 

 either no pores at all or 2-5 extremely large fenestrae. The broad aperture, which has a concave proxi- 

 mal rim, is provided with a more or less strongly chitinized operculum surrounded by a continuoiis 

 marginal thickening. No avicularia. The ooecium is enclosed in a kenozooecium, the frontal wall of 

 which is provided with a very large uncalcified part. Pore-chambers [dietellae] or groups of uniporous 

 rosette-plates [septulae]. 



The two known species classed in this family are Lepralia foraminigera Hincks, 

 1883, and Lepralia bilahiata Hincks, 1884. Levinsen believed that the second 

 species is probably the type of a special genus while the first is the type of the genus 

 Eurystomella. 



tat men 



Fig. 26. — Genus Eurystomella Levinsen, 1909. 



A-C. Eurystomella bilahiata Hincks, 1884. A. Sketch showing the operculum dissected out; r6, 

 outer rib; rb', inner rib; in. op., inner operculum; or, orifice; lat. mem., lateral membrane; fd. mem., 

 folded membrane; ac, accessory lip; ou. op., outer operculum. B. A few adult zooecia, X 30; th. r, 

 thickened rim; op, operculum; urn, umbo; /;, keel. C. A few zooecia at the growing edge of the colony 

 ehoiring the membranous aperture of the immature zooecia (im.. zoe.) (A-C, after Robertson, 1908.) 



D-F. Eurystomella foraminigera Hincks, 1883. D. Two gonozooecia and an ordinary zooecium, 

 X 40. E. Three zooecia, from the basal surface, which has a large uncalcified central part, X 40. F. A 

 sagittal section through a zooecium with ovicell, X 40. The orifice of the o^^cell is closed by the 

 ectocyet. (D-F, after Levinsen, 1909.) 



