44 Tlic American Geologist. j.-muary, i90o 
differs from it in bearing well marked furrows on the 
glabella. The head is somewhat distorted, but is nearly com- 
plete, even to the genal spines and the short spines included 
between these and the glabella. The greatest width of this 
head taken at the base of the genal spines is 21 m m., and 
its length, 13 m m. The glabella is 11 m m. long,* 6 m m. 
in maximum width and 5 m m. wide at its posterior extrem- 
ity. The right genal spine, which appears to be nearly per- 
fect, has a length of 2.5 m m. The occipital ring bears a short 
protuberence, which is probably the base of the dorsal spine. 
Several fragments of small heads probably belong to this 
form, but have not as yet been positively identified with it. 
The hypostomae and the fragments of the doublure are 
referred to this form from their general resemblance to those 
figured by Walcott (loc. cit. PI. xcii, figs. le and if.) and be- 
cause they occur in association with Holmia fragments. In 
no case has a hypostoma been found attached to or even 
closely associated with a doublure. The hypostomae appear 
to have belonged to rather large individuals. The smallest, 
which is also the most perfect, has a length of 16 m m. The 
width of the central convex portion is 11 m m. and the total 
width appears to be 15 m m. 
The many fragments of spines and pleurae appear to be- 
long generally to this species. The spines are ornamented 
with the raised fretwork characteristic of the genus Ollenellus. 
Some of the fragments have evidently been derived from in- 
dividuals of large size. One genal spine in particular has a 
maximum diameter of 17 m m. (Compare Walcott, loc. cit. 
PI. xcii, fig. if.) It is true, however, that a portion of this 
width is due to compression. 
Several fragments are believed to represent the dorsal 
spine of this form. One of these has escaped compressio!i 
and appears in something like its true relation, to a fragment 
of the occipital ring which has remained attached to its base. 
This spine is 4 m m. in diameter at the base and 3 m m. at its 
]:)roken end, 14 m m. from the base. 
*In measuring the length of the glabella the occipital ring is included. 
