196 Dr. H. Woodward—On some remarkable Cystideans. 
at its base and join with it to form the lower border of the body, and 
rest upon the two narrow ‘basals’ that encircle the attachment for 
the column. Above these is a second horizontal series of four plates, 
resting upon and alternating with the plates beneath. In this way 
the suture becomes median, and it is upon this suture, and towards 
the middle of the two centre plates, that the “anal plate” is situated ; 
it is circular and about 8 mm. in diameter. The series which 
follows that inclosing the anal plate is only composed of three 
plates, a little longer than broad, alternating with those which serve 
as their supports, the median plate being the broadest. The summit 
is also composed of three small plates, of which, as in the preced- 
ing, the centre one is the largest. 
The plates covering the body, with the exception of the small 
‘anal,’ ‘ ovarian,’ and ‘ basal plates,’ are all similarly ornamented with 
fine raised wavy striz running obliquely-transversely across their 
surface.' This well-marked ornamentation has been observed by H. 
Billings (Montreal), Prof. Jas. Hall (Albany, N.Y.), and F. B. Meek 
(Cincinnati), as characteristic of American species of Cystoidea 
belonging to this group. 
In the Grotocican MaGazine for 1871, Vol. VIII. pp. 71-72, L 
published a “‘ Note ona New British Cystidean,” with a woodcut 
giving figures of anterior and posterior side of Ateleocystites (Placo- 
cystites) Forbes, De Koninck sp., together with a note by Mr. E. 
Billings, which I here reproduce :— 
“ DEAR Str,—Ssir W. HE. Logan gave me your sketch of Placocystites, 
and I have this morning re-examined all of our specimens, and also 
compared Prof. de Koninck’s figures and descriptions in the article 
in the Grout. Mac. to which you refer. Placocystites and Ateleo- 
cystites are undoubtedly the same, as suggested by you. 
“ Anomalocystites, Hall (Pal. N.Y., vol. iii. p. 134, pl. 7a and 88), 
is also the same genus. The number of plates is different in the 
English, Canadian, and New York species, but this does not matter 
in such a genus of Cystideans as this. Since my Decade was pub- 
lished, we have collected several additional specimens of A. Hualeyi, 
but, unfortunately, none of them give any new information. ‘They 
are all imbedded in the rock, and all show the same—the concave 
side. The four species—Ateleocystites Hualeyi, Billings, Lower Sil. ; 
Placocystites Forbesianus, De Koninck, Upper Sil.; Anomaiocystites 
cornutus, Hall, Upper Sil.; Anomalocystites disparilis, Hall, Devonian 
—are all composed of a limited number of plates not arranged in 
regular series, their bodies convex on one side and concave on the 
other. The first three have the plates transversely striated in a 
peculiar manner, and most probably good specimens of the fourth 
would show the same surface character. This striation is of the 
1 T am only acquainted with one other organism from the Upper Silurian rocks 
which is similarly ornamented, namely, the plates of Taurrilepas. 
Future discoveries may possibly enable us to correlate this anomalous Cirripede (?) 
ue our Ateleccystites, but at present we have not the evidence before us tor 
doing so. 
