MOLLUSCOIDEA. 347 



Genus Micropora Gray. 



Micropora cylindracea TJlricli and Bassler n. sp. 



Plate XXV., Fig. 4. 



Description. — Zoarium consisting of cylindrical stems about 

 0.5 mm. in diameter, celluliferous on all sides with about nine 

 longitudinal rows of zooecia. Zooecia elongate, subelliptical in 

 outline, slightly truncated posteriorly by the rounded end of the 

 one next behind, about 0.5 mm. in length with the width a little 

 less than one-half the length, surrounded by a slightly raised, 

 narrow, convex border. Zooecial apertures anterior, small, 

 subsemicircular in outline, nearly twice as wide as long. Back 

 of the aperture the surface of the zooecia is covered by a 

 thin, flat wall, slightly depressed below the raised zooecial mar- 

 gin, through which a little in front of the mid length of the 

 zooecium, there is a pair of small, longitudinal, slit-like pores, one 

 on each side close up to the raised border. Avicularia frequently 

 present, situated in the lower, right-hand corner oi the zooecia. 



Formation and locality. — ^Vincentown limesand, Viticentown 



(154). 

 Geographic distribution. — New Jersey. 



Micropora pulchra Ulrich and Bassler n. sp. 



Plate XXV., Fig. 3- 



Description. — Zoarium consisting of cyhndrical branches, 0.5 

 mm. to I mm. in diameter, which divide dichotomously, with 

 zooecial openings on all sides, the openings arranged in from 

 6 to 9 longitudinal rows. Zooecia rather narrowly elongate, 0.6 

 mm. to 0.7 mm. in length, with the width less than one-half the 

 length, rounded anteriorly and truncated posteriorly by the 

 rounded extremity of the zooecium just behind, surrounded by a 

 low, narrow, ridge-like border. Zooecial apertures anterior, 

 rather small, transversely subelliptical in outline, their length 

 about two-thirds their width ; back of the aperture the surface of 

 the zooecia is covered with a thin, slightly convex wall, without 

 perforations, a little depressed below the marginal border. Just in 



