738 SYSTEMATIC PALEONTOLOGY 



length and from 0.1 mm. to 0.13 mm. in width, the lateral boundaries 

 sharply defined by impressed grooves, the surface gently convex trans- 

 versely. Zoeficial apertures nearly terminal, circular, a little narrower 

 than the zocecia, directed slightly forward, with a slightly elevated rim- 

 like bordjer. 



This species cannot be confused with any associated bryozoa, the other 

 American species of the genus being mainly of Ordovician age. The 

 species is particularly characterized by its small, narrow, elongate 

 zooecia, with each zocecium sharply marked laterally. 



Occurrence. RANCOCAS FORMATION. ISToxontown Millpond, Delaware. 



Collection. Maryland Geological Survey. 



Family 1DMONEIDAE 

 Genus CRISINA d'Orbigny 

 CRISINA STRIATOPORA Ulrich and Bassler 



Plate XL VI, Fig. 15 



Crisina striatopora Ulrich and Bassler, 1904, Maryland Geol. Survey, Mio- 

 cene, p. 406, pi. cxvii, figs. 1-4. 



Crisina striatopora, Ulrich and Bassler, 1907, Geol. Survey of New Jersey, 

 Pal., vol. iv, p. 319, pi. xxi, figs. 15-18. 



Description. Zoarium. erect, ramose, probably not exceeding 1 cm. in 

 height, dividing dichotomously at intervals of about 1.5 mm.; branches 

 subovate in cross-section, thickest uniformly convex and traversed longi- 

 tudinally by from sixteen to twenty punctate strire on the reverse side, 

 narrower and carrying alternating series of zococial apertures on the 

 obverse side. Zooecial apertures rarely three, usually four in each series, 

 in contact laterally, the inner one of each series largest, most prominent 

 and subcircular, the outer one smallest, drawn out distally and apparently 

 grading into the pores lying between the longitudinal ridges of the 

 reverse side. Series of zocecia curving first forward then slightly back- 

 ward, separated by a deep interspace averaging about 0.2 mm. in width ; 

 about five rows in 2 mm. Over the basal part of the zoarium the zocecial 

 apertures are covered one after the other by the growth of the striato- 

 punctate dorsal integument. 



