NORTH AMERICAN LATER TERTIARY AND QUATERNARY BRYOZOA. 71 



HEMISEPTELLA GRANDICELLA Canu and Bassler, 1919. 



Plate 5, fig. 12. 

 1919. Hemiseptclla grandicella Canu and Bassler, Geologj- and Paleontology- of the West Indies, Bry- 

 ozoa, Publications of the Carnegie Institution of Washington, No. 291, p. 84, pi. 5. fig. 11. 



Description. — The zoarium incrusts shells. The zooecia are large, elongate, 



ogival, distinct, separated by a furrow of little depth; the mural rim is narrow, little 



saHent, round, finely granulated; the cryptocyst is large, flat, granulated; the ope- 



sium is elongated, elliptical, irregular and nonsymmetrical in the proximal portion. 



,, ^ r\ ■ fAo = 0.40 mm. „ ■ [is = 0.65-0.70 mm. 



Measurements. — Upesia , „ „^ Ziooecia , „ _. 



^ I (0 = 0.25 mm. [Zs = 0.3omm. 



Affinities. — The group of inferior opesiular spines was certainly dissymmetrical; 

 trace of the lateral spines is scarcely visible on our specimens. 



This species differs from Hemiseptella denticulata Smitt, 1872, in the absence of 

 nodosities in the interzooecial angles and in the nontrifoliate opesium. It differs 

 from Hemiseptella tenuis Desor, 1S48, in the larger micrometric measurements and 

 in the more fragile and less numerous spines. 



Occurrence. — Lower Miocene (Bowden marl) : Bowden, Jamaica (rare) . 



Holotype. —C&t. No. 68490, U.S.N.M. 



HEMISEPTELLA FILIMAKGO, new species. 



Plate 10, fig. 9. 



Description. — The zoarium incrusts shells. The zooecia are distinct, separated 

 by a very tliin salient thread, elongated, subhexagoQal; the mural rim is very thin, 

 filiform, salient; the cryptocyst is large, flat, shallow. The opesium is semielliptical, 

 transverse, with an irregular proximal border, two large lateral spicules and many 

 spicules placed inferiorily. 



,, . /-> ■ l/io = 0.12-0.18 mm. „ ■ (is = 0.40-0.50 mm. 



Measurements. — Opesia , „ , - r. «/^ Zooecia , r^ nr n nn 



^ { Zo = 0.15-0.20 mm. [ fe = 0.25-0.30 mm. 



Variations. — The micrometric measurements are very irregular. Interzooecial 

 tubercles are sometimes present. On our single specimen the spicules are badly 

 preserved. The extreme thinness of the mural rim well characterizes this species. 

 Cases of regenerated zooecia have been observed. 



Occurrence. — Miocene (Yorktown formation) : York Kiver, Virginia (very 

 rare). 



Holotype.— Cat. No. 68491, U.S.N.M. 



HEMISEPTELLA TUBERGSA. new species. » 



Plate 46, fig. 10. 



Description. — The zoarium incrusts shells. The zooecia are distinct, elongated, 

 rectangular, ornamented with large interzooecial tubercles; the mural rim is thick, 

 rounded, granulated; the cryptocyst is much reduced, deep, granulated. The 

 opesium is elongated, elliptical, with an irregular proximal border. 



,, , r^ . 1^0 = 0.25 mm. „ . (Z2 = 0.35 mm. 



Measurements. — Opesia , _,. Zooecia , r> o=: ™~ 



^ l/o = 0.15mm. I te = 0.25 mm. 



Variations. — On our type specimen there are very few spicules visible. The 



micrometric measurements are very irregular. 



