Helopora.] BEYOZOA. 19f 



Helopora harrisi James. 



PLATE III. FIGS. 1], b,e. and 12. 



Helopora harrisi James, 1883. " The Paleontologist," p. 58. 



Segments very small, acerate, about 3.5 mm. long, 0.22 mm. thick, hexagonal in 

 cross-section; upper extremity slightly expanded, conical or pyramidal, with the 

 angles prominent, the lower end striated, tapering, obtusely pointed or slightly 

 bulbous ; between the ends the sides are nearly parallel. Zooecia in six longitudinal 

 ranges, their apertures small, narrow-elliptical, often drawn out anteriorly, their 

 margins thickened, about twice their length apart, with seven (usually) on each of 

 the six faces. Peristomes connected lengthwise, their sides being co-incident or 

 merged into the moderately develope'd ridges forming the angles of the segment. 

 The later are nearly always straight. Interspaces between the ends of the zooecial 

 apertures occupied by a low rounded ridge, rising and spreading at each end into 

 the peristomes. The best preserved examples exhibit a row of exceedingly minute 

 papillae on the peristomes and angle-ridges. 



In transverse sections the zooecia appear as six subequal wedge-shaped cells, 

 arranged around the central axis. The outer investment is rather thin, but in most 

 cases the projecting angles and the intermediate ridges are distinguishable. In 

 vertical sections the anterior side of the zooecia is nearly straight, forming an angle 

 of about fifty degrees with the axis. The zooecia are comparatively elongate, but the 

 overlap is unusually little. Sections on the whole are much like those of Nematopora 

 lineata Ulrich, as figured in Vol. viii, 111. Geol. Sur., pi. XXIX, fig. 7, but the zooecia 

 are more elongate in H. harrisi. 



I cannot doubt that this is the species named by Mr. James in the publication 

 cited above, since the greater part of my specimens are from the same spot and 

 layer that furnished his types. But for this certainly I would not be able to identify 

 the species, Mr. James' description being very incomplete and incorrect in some of 

 the points mentioned by him. I succeeded in obtaining free from the matrix fully 

 one thousand segments, and as many of these as have been examined show clearly 

 and uniformily six rows of cells, not two, three, or four as he supposed. He states 

 also that the sides are constricted at the ends of the apertures, "giving them a chain- 

 like appearance." This is most certainly not true of any specimen seen by me. His 

 figures of .the species too are as little or even less trustworthy. Indeed the two plates 

 which accompany that number of "The Paleontologist" may be said to burlesque 

 art illustration.* 



*lt Is really a fair question whether a species so illy and insufficiently characterized as this, has any claim to 

 itlon In this case It luippened that I had selected the same specific name for it, we having both intended to honor 

 M°°I°H H'lrris of Waynesville, Ohio, who sent each of us one of the original specimens. 



