„ , , BRYOZOA. 205 



Nematopora.] 



short ridge joins the peristomes of each row of apertures, and longitudinally divides 

 the concave spaces between the ends of the apertures. These spaces are larger in 

 the subquadrate examples than in those having five rows of zooecia. They also have 

 tlie thin ridge that bounds each face more distinct from the elevated margins or 

 peristomes of the zocecial apertures, which, in the pentagonal specimens, to a large 

 extent also form the border of the faces. Longitudinal interspaces generally shorter 

 than the length of the zocecial apertures ; about five of the latter in 2.5 mm." 



Careful comparisons between the New York types of Nematopora quadrata {he. cit.) 

 and the originals of N. ovalis have convinced me of their specific identity. My belief 

 that the latter had larger zooecia proved incorrect, and as many of them have also 

 the double ridges at the angles of the branches, which were regarded as the main 

 peculiarity of the former, nothing is left to distinguish them. It is to be admitted, 

 however, that none of the New York examples of the species so far seen have more 

 than four rows of zooecia. 



The large size of its zocecial apertures will distinguish N. ovalis from the three 

 species next described. N. lineata Billings, sp., of the Anticosti group, is a larger 

 species with six or seven rows of zooecia. 



Formation and Zoea/%.— Galena shales, near Cannon Falls, Minnesota; Trenton limestone, Trenton 

 Falls, New York, and Montreal, Canada. 



Mus. Beg. No. 8110. 



Nematopora granosa Ulrich. 



PLATE III, FIGS. 17-20. 



Nematopora granosa Ulkich, 1890. Jour. Cin. Soc. Nat. Hist, vol. xii, p. 196. 



Original description: "Zoarium ramose; branches bifurcating at rather long 

 intervals, from 0.25 to 0,38 mm. in diameter, the smallest quadrangular in cross- 

 section and with only four rows of zooecia ; those of the average size, pentagonal, 

 and with five rows of cells. Zocecial apertures small, narrow, about seven in each 

 range.in 2,5 mm,, enclosed by a series of minute granules. Longitudinal interspaces 

 with a small number of similar granules. Rows of apertures separated by more or 

 less well-developed straight or slightly fiexuous granulose ridges." 



The papillose ornamentation of the ridges and interspaces, and the narrowness 

 of the zocecial apertures of this species distinguish it from all the others having the 

 essential characters of Nematopora known to me. Under the microscope the general 

 appearance of the zoarium is strikingly different from that of N. ovalis, with which 

 it is associated. Equally marked differences will be noted when it is compared with 

 N. delicatula and N. conferta, both of which likewise occur in the same beds. 

 Externally N. granosa presents not a little resemblance to small species of Ehombo- 



