BRYOZOA. ' 649 



* 



RHOMBOPORA SULCIFERA Ulrich. 



PL XLV, Fig. 2-Ub. 



Zoarium consisting of slender cylindrical stems, 1 mm. or a 

 little more in diameter, none of which were observed to branch, 

 though probably doing so at long intervals. Zocecia apertures 

 oval, about 0.17 by 0.08 mm., arranged in diagonally inter- 

 secting series, crossing each other at an angle of about 90, 

 with eight or nine in 2 mm., measuring diagonally, and about 

 six in the same space longitudinally. Interspaces as wide or 

 wider than the apertures. A considerable number of small 

 spines encircle the apertures, and are often arranged in a double 

 series. In the latter case the center of the interspace is de- 

 'd. so that the apertures appear to be surrounded by a 

 granulose peristome. The distinctness of this furrow, which has 

 suggested the specific name, depends largely upon the preserva- 

 tion of the specimen. Beside the small spines, a less numerous 

 series of larger size are present, generally one between the ends 

 of the apertures. In tangential sections the small spines are 

 noticed only in the extreme outer region of the zoarium, while 

 the larger ones extend inward to a greater depth. 



The smaller size of the branches, the depressed interspaces, 

 and their great thickness in tangential sections, distinguish the 

 species from R. subannulata. 



Position and locality: Hamilton group; Davenport, Iowa. 

 The specimens were presented to the author by Rev. W. H. 

 Bams of Davenport. Iowa. 



RHOMBOPORA LIXEINODIS Ulrich. 



PL XLV, Figs. -3b. and (?) 4-la. 



Zoarium consisting of slender stems from 0.5 to 0.8 mm. in 

 diameter, branching dichotomously at intervals of from 3 to 6 

 mm. Surface appearing beaded from the large number of small 

 spines arranged serially and close together on straight or flexu- 

 ous, elevated, rounded ridges, running parallel with the length 

 of the branches between the rows of apertures. In young ex- 

 amples these ridges are generally more flexuous than in the 

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