MOLLUSCOIDEA. 319 



towards the anterior carina and arranged in more or less irregular 

 transverse series, about five or six occupying the space of I mm. ; 

 posteriorly they become more scattered and may become entirely 

 wanting upon the rounded posterior surface. Zocecial apertures 

 subcircular or oval, slightly oblique, surrounded by a slightly 

 raised peristone which is a little higher behind than in front. 

 Smaller mesopores occupy the spaces between the zocecia. 



Remarks. Besides its occurrence in the Vincentown limesand, 

 this species has also been recognized in the Eocene of Maryland. 

 A very similar, perhaps identical, form from the Upper Cre- 

 taceous (Senonien) of France has been described under the name 

 Bicrisina. gaudryana Pergens. 1 



Formation and locality. Vincentown limesand, Vincentown 

 (154), Timber Creek (Gabb and Horn). 



Geographic distribution. New Jersey, also Eocene of Mary- 

 land. 



Genus CRISINA d'Orbigny. 



Crisina striatopora Ulrich. 

 Plate XXL, Figs. 15-18. 



1904. Crisina- striatopora Ulrich, Md. Geol. Surv. Miocene, p. 

 406, pi. 117, figs. 1-4. 



Description. "Zoarium erect, ramose, probably not exceeding 

 i cm. in height, dividing dichotomously at intervals of about 1.5 

 mm.; branches subovate in cross-section, thickest uniformly 

 convex and traversed longitudinally by from 16 to 20 

 punctate striae on the reverse side, narrower and carrying alter- 

 nating series of zo'cecial apertures on the obverse side. Zocecial 

 apertures rarely three usually four in each series, in contact later- 

 ally, the inner one of each series largest, most prominent, and 

 subcircular, the outer one, smallest, drawn out distally and ap- 

 parently grading into the pores lying between the longitudinal 

 ridges of the reverse side. Series of zocecia curving first forward 

 then slightly backward, separated by a deep interspace averaging 



1 Bull. Soc. Belg. de Geol., vol. 3, pi. 13, fig- 2. 



