BRYOZOA. 657 



The position of this species is doubtful, and more material IB 

 required before its relations can be determined satisfactorily. 

 It may turn out to be a Streblotrypa. 



Position and locality: Keokuk group, King's Mountain, Ky. 



RHOMBOPORA SIMULATRIX Ulrich. 



PL LXXI, figs. 2-2e. 



Zoarium ramose, branches slender, varying from 1.0 to 2.1 

 mm. in diameter, dividing dichotoinously at intervals of from 

 10 to 15 mm. Zocecia apertures oval, averaging 0.12 mm. in 

 length, arranged in only moderately regular, diagonally inter- 

 secting and longitudinal series, with sometimes one and then 

 the other arrangement the most noticeable. Measuring longi- 

 tudinally, five or six apertures occur in 2 mm.; diagonally, nine 

 in younger examples and eight in the older ones in 2 mm. In- 

 terspaces becoming natter and increasing in thickness with age, 

 usually wider than the zooecia apertures; in the young examples, 

 narrowly rounded, and crowned with a single series of small, 

 close set granules, with one of larger size between the ends of 

 the oval depressed areas. On the larger specimens the inter- 

 spaces may be nearly flat and occupied by two or three rows of 

 granules. 



The internal characters of a mature example are very well 

 shown in figs. 2d and 2e. 



This species resembles several others but is really not very 

 closely related to any. Small specimens present external resem- 

 blance to R. minor, of the Chester group, but the internal struc- 

 ture of the two is quite different, and points rather to a rela- 

 tionship with R. wortheni and R. decipiens. 



Position and locality: St. Louis group, at Columbia and other 

 localities in Monroe county, 111. 



RHOMBOPORA DECIPIENS Ulrich. 



PI. LXXI. flg. 3-3d. 



Zoarium ramose, the branches rather robust. 1.5 to 3 mm. 

 in diameter, divided dichotomously at variable interval*. Zo- 

 recia apertures oval, a little oblique, averaging 0.15 mm. in 

 length by 0.10 mm. in width, arranged in more or less inter- 

 rupted lines, which may be vertical, diagonal, or transverse. 

 82 



