Fig-. 18. 
Fig. 19. 
Fig. 20. 
Figs. 21, 
Fig. 23. 
Fig. 24. 
Fig. 25. 
Fig. 26. 
Fig. 27. 
Fig. 28. 
Fig. 29. 
Fig. 30. 
Fig. 31. 
Fig. 32. 
Fig. 33, 
Fig. 34, 
Fig. 35 
PLATE IVH—Continued. 
Crania setifera, Hall. 
A somewhat imperfect upper valve. 
Niagara group. Waldron, Indiana. 
Crania gbanosa, sp. nov. 
A somewhat distorted upper valve ; showing the finely granulose surface. 
A portion of the surface enlarged. X 20. 
Hamilton group. Centerfield, N. Y. 
Crania Trentonensis. Hall. 
22. Front and profile views of an upper valve. 
Trenton limestone. Middleville, N. Y. 
Crania scabiosa, Hall. 
A brachial valve of Strophovieua alternata, covered with shells of this species all of which carry 
the radiating- and fine concentric ornamentation of the host. 
The interior of an upper valve, the external surface of which is overgrown by a Monticulipora. 
The posterior adductors are larger than the anterior pair, and near their outer edges the small 
scars of the adjustors are discernible. In this species as usually preserved the muscular im¬ 
pressions appear as dark discolorations of the shell, indicating a probable greater density of 
the shell-substance. X 2. 
The interior of a lower valve. The posterior scars are more distant and smaller than in the 
opposite valve, while the anterior scars are much larger. X 2. 
A shell of Platystrophia lynx, having the surface of the brachial valve crowded with individuals 
of this species. 
Hudson River group. Cincinnati, Ohio. 
Crania multipunctata, Miller (= Crania scabiosa , Hall). 
One of a group of individuals attached to a fragment of Monticulipora. The punctate surface 
character of the host is impressed upon the shell, giving it a remote resemblance to the surface 
of Trematis terminalis. X 2. 
Hudson River group. Covington, Ky. 
Another specimen with similar surface markings. X 2. 
Hudson River group. Blanchester, Ohio. 
Crania socialis, Ulrich (Hi Crania scabidsay Hall). 
A fragment of a crinoid column, coverefi with individuals which retain very distinctly the impres¬ 
sions of the sutures between the segments. X 3. 
Hudson River group. Covington, Ky. 
Crania percarinata, Ulrich (= Crania scabiosa^ Hall). 
An individual which has been attached to some species of Pleurotomaria. X 3. 
Another specimen, which also bears the surface markings of some gastropod. X 3. 
Hudson River group. Covington, Ky. 
These figures are from Mr. Ulrich’s typical specimens. 
- Crania, sp. nov. ? 
The interior of an upper valve of a probably smooth species. X 2.. 
Lower Helderberg group. Near Clarksville, N. Y. 
Crania favincola, sp. nov. 
, A lower valve, slightly broken about the posterior margin, but showing the very large posterior 
muscular impressions, the deeply impressed anteriors, with sharply elevated margins and 
median fulcrum; also, the radiating pallial sinuses. The shell is attached to a specimen of 
Favosites pirum, Davis. 
Hamilton group. Crab Orchard, Ky. 
Crania Leoni, Hall. 
. The interior of an upper valve; showing, in addition to the posterior and anterior adductor scars, 
the faint impressions of the brachial muscles 
. The exterior of an upper valve. 
Chemung group. Leon, N. Y. 
