VIII. Cyathocrinus. 213 
Cyathocrinus in Silurian rocks, we now know a considerable 
number of Silurian species that may be referred to this genus. 
The Limestone Beds d and f of Gotland furnish nine species 
of Cyathocrinus, as described in a paper read before the Royal 
Swedish Academy of Science on Dec. 9th, 1891*. The 
Niagara Limestone of America contains Cy Goering: cord, 
Hall, C. waukoma, Hall, and C. Van Horned, 5S. A. Miller; 
but other Silurian species from N. America appear to belong 
rather to Botryocrinus. The Wenlock Limestone of England 
has as yet presented us with only two species, viz. C. acino- 
tubus, Ang., also found in Gotland (d and /’), and a species 
here described for the first time under the name C. vallatus. 
As shown in the paper above referred to, the Cyathocrini of 
Gotland fall into three groups. The first of these groups has 
a stem of moderate width, with rather low and alternately 
ridged columnals and a more or less conical cup. Both our 
British species come into this group, and the following 
synopsis shows the main differences between the species of 
the group :— 
a, Cup with straight sides, 
Greslates, plane, Oranulaty Wis ccqiee aula je hae atin wai C. Diane. 
6. Plates axially folded and striate ................ C. striolatus. 
b. Cup with conyexo-concave sides, irregular. 
c. Plates plane; smooth or pustulate .............. C. visbycensis. 
d, Plates tumid ; smooth or shagreened ............ C. acinotubus, 
ce. Cup with convex sides. 
e. Plates plane ; concentrically ridged and pustulate.. C. vallatus. 
There are of course many other differences between the 
species than those shown in the above table, but they can be 
gathered from the diagnoses. 
Cyathocrinus acinotubus, Ang. 
(PI. XII. figs. 1-13.) 
1878. Cyathocrinus acinotubus, Angelin, Iconographia, p. 22, pl. xx. 
fio. 5, 
ae eee alutaceus (pars), Angelin, Iconographia, pl. iv. 
£ a 
1873. Cyathocrinus (sp. 6) monile, nom. nud., Salter, ‘Catalogue of 
Cambrian and Silurian Fossils &c.,’ Cambridge, p. 125. 
* EF. A. Bather, “The Crinoidea of Gotland, Part I,” Kel. Svenska 
Vet.-Akad. Handl. Bd. xxiv. no. 8. In the press. 
