MARYLAND GEOLOGICAL SURVEY 213 



Trenton localities some have more than commonly swollen and crowded 

 cells, while in some of those from the geologically higher localities the 

 growth is lax and the zocecia comparatively narrow." Ulrich, 1893. 



Occurrence. CHAMBERSBURG LIMESTONE (Nidulites bed). Wilson, 

 Maryland. 



Found in the Black River-Richmond at many localities in the United 

 States and Canada. 



Collections. Maryland Geological Survey, U. S. National Museum. 



CORYNOTRYPA DELICATULA (James) 



Plate XLVII, Figs. 12-14 



Hippothoa delicatula James, 1878, The Paleontologist, No. 1, p. 6. 

 Stomatopora tenuissima Ulrich, 1893, Geol. Minnesota, vol. iii, pt. 1, p. 116, 



pi. i, figs. 16, 17. 

 Stomatopora proutana Ulrich, 1893, Geol. Minnesota, vol. iii, pt. 1, p. 117, 



pi. i, figs. 8-12. 

 Corynotrypa delicatula Bassler, 1911, Proc. U. S. Nat. Mus., vol. xxxix, 



p. 506, text figs. 3a, 4-7. 



Description. This neat incrusting fossil is extremely abundant in 

 America where it is known in most of the Ordovician formations, begin- 

 ning with the Stones River. The zocecia vary considerably in size in the 

 different forms of the species, but maintain the same relative proportions. 



In both the .large and small forms the zoarium is incrusting and con- 

 sists of uniserially arranged, slender, club-shaped zocecia, increasing 

 gradually in size from the narrow proximal end to the rounded anterior 

 portion. The aperture is small, sub terminal, with a slightly elevated 

 border, and about one-third the diameter of the anterior third of the 

 zocecia. The measurements for the two forms are as follows: Typical 

 specimens have zocecia 0.04 mm. in diameter at the proximal end, increas- 

 ing to 0.12 to 0.15 mm. at the widest part of the rounded anterior por- 

 tion. The zocecia vary from 0.6 to 0.8 mm. in length, and 8 to 10 occur 

 in 5 mm. The larger form varies from 0.8 to 1.1 mm. in length and 

 from 0.2 to 0.3 mm. in diameter at the anterior portion. The stolon is 

 of variable length. The angle of divergence in both large and small 

 zocecia is about 15. 



