68 BULLETIN 77, UNITED STATES NATIONAL MUSEUM. 



CORYNOTRYPA DISSIMILIS (Vine). 



Text fig. 14. 



Stomatopora dissimilis Vine, Quart. Journ. Geol. Soc. London, vol. 37, 1881, pp. 



615, 616, figs. 1-8; vol. 38, 1882, p. 50.— Bassler, Bull. 292, U. S. Geol. Surv., 



1906, p. 15, pi. 4, figs. 15-19. 

 Stomatopora recta Ringueberg, Bull. Buffalo Soc. Nat. Hist., vol. 5, 1886, p. 20, 



pi. 2, figs. 15, 15a. 

 Stomatopora minor 'K'E.-HT^iG, Arkivfur. Zool., Kong. Sven. Vet.-Akad. Stockholm, 



vol. 3, No. 10, 1906, p. 24, pi. 3, fig. 6. 

 Aulopora, species. Hall, Nat. Hist. New York, Pal., vol. 2, 1852, pi. 50, figs. 



27, 29. 

 Corynotrypa dissimilis Bassler, Proc. U. S. Nat. Mus., vol. 39, 1911, p. 523, text 



fig. 23. 



The identification of this species in Russian strata is based on speci- 

 mens from the Lyckholm limestone differing in no appreciable manner 



Fig. 14.— Coeynotrtpa dissimilis. a and 6, a typical example of the species, x9 and X20, mcEXJSTmG 



THE EPITHECA OF THE BEYOZOAN DiPLOTRYPA NUMMIFOEMIS. SiLUEIAN, ROCHESTEE SHALE, LOCKPOET, 



New York; c and d, poorly peeseeved specimen of the species, X9 and X20, geowing upon 



A SPECIMEN OF HELIOLITES. EaELY SiLUEIAN, LYCKHOLM FORMATION, KeETEL, ISLAND OF DaGO 

 ESTHONIA. 



from the common Middle Silurian Corynotrypa dissimilis. The zoa- 

 rium is parasitic, consisting of uniserial branching zooecia, subcylin- 

 drical or club-shaped, 0.15 to 0,20 mm. in diameter at the proximal 

 end and increasing slowly to twice this width at the widest portion 

 of the distal end. Average zooecia are 1.15 mm. in length, with 

 5 to 6 in 5 mm. ; the apertures are subterminal, bounded by a slightly 

 developed, rim-like border and so large that they occupy more than 

 three-fourths of the zooecial diameter. The typical form of the spe- 

 cies, however, is well marked transversely by fine wrinkles or stria- 

 tions. In the Russian specimens these striations are absent entirely, 

 the surface being smooth and minutely porous as in other species 

 of the genus. Aside from the absence of transverse striations, the 

 zooecia in these specimens show a tendency to be slightl}^ larger and 



