390 
VINE: NOTES ON FOSSIL POLYZOA. 
rhomboidal to hexagonal vestibules." Ridges separating vestibules 
spiniferous, spiues hollow, often of two kinds, large and small, the 
latter most numerous, and surrounding the apertures in a single or 
double series, while the larger spines are usually developed only at 
the upper extremity of the cell."* 
Type of Genus R. lejndodendroidea, Meek, Upper Coal Measures, 
Western States : Nebraska and Wyoming. My type specimens are 
from the Chester Carb. Series. U.S., America. 
1 ? Rhombopoea lepidodendeoidea, Meek. 
Palaeontology Eastern Nebraska, Meek, 1871, p. 141, pi. VII, fig. 2. 
Uli-ich, Jour. Cincin. Soc. Nat. Hist., April, 1884, pi. I., fig. 1, la, & 16. 
In the Yorkshire shales I have two or three specimens that I 
rather hesitate to place here as identically the same as the American 
species, but if not the same, the species is a very close ally, but 
much more slender than the American form. 
Locality: Hurst, North Yorkshire. 
2. Rhombopoea peesimilis, Ulrich. 
Jonr. Cincin. Soc, Nat. Hist., Ap., 1884, p. 30, pi. I, fig. 7a, Id. 
The Zoarium of this species is ramose and slender, but far more 
bulky than the more delicate, or even the robust forms of Rhahdo- 
meson gracile, Phill. The mode of branching, however, is the same ; 
thrown off at right angles from the main stem. Zoaecia arranged very 
regular in vertical series ; apertures elliptical and ornamented by 
larger spines at the bottom of each aperture, and by very delicate 
spines on the margins of the cells. The vestibules of the Yorkshire 
specimen are similar to that figured by Mr. Ulrich, and allowing for 
slight variations, I regard the Yorkshire and the American forms as 
identical as forms so widel}^ separated could possibly be. Mr. Ulrich, 
however, says (op. cit., p. 30) " It is almost impossible to separate 
fragments of Rhombopora persimilis from those of Rhabdomeson 
gracile, Phill. by their external character. Sections of the two forms 
show conclusively that the two are different." This opinion, how- 
ever, must be somewhat qualified as regards the Yorkshire specimens, 
for though these now described have lain by me for years, I have 
refused to lable them R. gracile ; and when seen side by side with 
* Two sentences left out which have reference to Diaphragms and centrally 
perforated opercular. 
