Corals and Briozoans of the Lower Helderberg. 143 

 aulopora subtenuis, 71. sp. 



(PLATE II, FIGS. 9-18 ) 



Corallum consisting of elongate, slender, tubular cells, very gradually enlarg- 

 ing to the aperture, generally only a single budding, but sometimes two, and 

 very rarely three. Cell-tubes straight to the point of budding, when they 

 abruptly turn to one side. Length about eight mm. ; diameter at aperture one 

 mm., at smaller end, .75 mm. Sometimes quite strongly corrugated and lon- 

 gitudinally striated ; surface in some specimens apparently papillose. 



This species may be distinguished from A. Schoharice by its more slender 

 form, greater length, and by its mode of budding. In A. /Schoharice, where 

 two buds proceed from one tube, they are at about the same • distance from the 

 aperture, and one on each side of a central line, and the cell ceases to grow 

 after budding, while in this species the buds are in the centre of the posterior 

 part of the tube in a direct line, and sometimes two mm. apart. In all the 

 specimens, so far seen, the apertures do not turn upward after budding, but to 

 one side. 



Formation and locality. Lower Helderberg group, near Clarksville, N. Y. 



AULOPORA ELONGATA, 71. Sp. 

 (PLATE II, FIGS. 19, 20.) 



Corallum consisting of comparatively large, cylindrical, tubular cells, increas- 

 ing by one or two buds from each cell ; when two, they are bilateral. Length 

 of tubes about eight mm.; diameter at apertures two mm.; corrugated and 

 striated longitudinally. 



Formation and locality. Lower Helderberg group, Schoharie, N. Y. 



AULOPORA P^CORNULITES, 71. Sp. 



(PLATE II, FIGS. 21, 22.) 



Length of tube six mm. ; diameter at the apertures a little less than two mm. ; 

 surface marked by numerous, comparatively strong transverse annulations, and 

 by longitudinal striae. 



Formation and locality. Lower Helderberg group, near Clarksville. NY. 



VERMIPORA, Hall. 

 Vermipora. serpuloides. 



(PLATE II, FIGS. 24-31.) 



Vermipora serpuloides. Hall. Twenty-sixth Rep. N. Y. State Mus. Nat. Hist., 



p. 110. 1874. 



Corallum ramose, solid, consisting of contiguous, cylindrical tubes, increasing 

 by interstitial additions. Branches from two to eight mm. in diameter. Tubes 



