EAELY PALEOZOIC BEYOZOA OF THE BALTIC PROVINCES. 61 



U.S.N.M.); and (3) several large colonies growing upon the cellulif- 

 erous face of Heliolites, from the Ljckholm limestone (F] ), at Hohen- 

 holm, island of Dago, Baltic Sea (Cat. No. 57183, U.S.N.M.). 



Numerous specimens from American localities are in the British 

 Museum. 



Genus CORYNOTRYPA Bassler. 



Corynotrypa Bassler, Proc. U. S. Nat. Mus., vol. 39, 1911, p. 501. 

 Stomatopora (part) of authors. 



This genus was recently instituted for the reception of species 

 hitherto assigned to Stomatopora, in which the zoarium consisted of 

 adnate, simple, subtubular zooecia arranged unilinearly but of a 

 distinctly oval-pyriform to elongate-clavate shape. The zooecium 

 is further distinguished by having its proximal end constricted and 

 united to the preceding zooecium by a narrow stolon of variable 

 length; the distal portion of the zooecium is expanded and bears the 

 aperture which is sabterminal, circular, and surrounded b}^ a more 

 or less distinctly elevated peristome; zooecial walls, as in Stomatopora, 

 finely porous. 



The points of agreement and difference between Stomatopora and 

 Corynotrypa may be easily discerned by comparing the illustration 

 of S. arachnoidea (fig. 7) with the views of C. delicatula and other 

 species figured on the following pages. In discriminating species 

 of Corynotrypa, the characters which have been found to be most 

 valuable are the size and shape of the zooecium and its angle of 

 divergence obtained by measuring the rate of expansion of its sides, 

 beginning at the distal end of the stolon. The slender, tubular 

 connecting portion designated the stolon is the most variable of all 

 characters and is consequently of little aid in the separation of species. 



Genotype. — Corynotrypa delicatula (James). Ordovician and early 

 Silurian of North America and Europe. 



CORYNOTRYPA DELICATULA (James). 



Text fig. 8. 



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



Stomatopora delicatula Nickles and Bassler, Bull. 173, U. S. Geol. Surv., p. 



419.— Bassler, Proc. U. S. Nat. Mus., vol. 30, 1908, p. 55, pi. 3, figs. 4-7. 

 Stomatopora proutana Miller, Journ. Cincinnati Soc. Nat. Hist., vol. 5, 1882, p. 



39, pi. 1, figs. 4-46. — Ulrich, Geol. and Nat. Hist. Surv. Minnesota, Final 



Rep., vol. 3, pt. 1, 1893, p. 117, pi. 1, figs. 8-12. 

 Rhopalonaria pertenuis Ulrich, Fourteenth Ann. Rep. Geol. and Nat Hist. Surv. 



Minnesota, 1886, p. 59. 

 Stomatopora tenuissima JJl^rics, Journ. Cincinnati Soc. Nat. Hist., vol. 12, 1890, 



p. 175, fig. 2; Geol. and Nat. Hist. Surv. Minnesota, Final Rep., vol. 3, pt. 1, 



1893, p. 116, pi. 1, figs. 16, 17. 

 Stomatopora delicatula-tenuissim^a Nickles and Bassler, Bull. 173, U. S. Geol. 



Surv., 1900, p. 419. 

 Corynotrypa delicatula Bassler, Proc. U. S. Nat. Mus., vol. 39, 1911, p. 506, text 



figs. 3a, 4-7. 



