ri^ATE IVh— Coiitiiuiei!. 



Crania setifera, Hull. 



Kijr. 18. A soiiiewliat imperfect upper val\e. 



Niag-ai'a group. Waldron, Indiana. 



Crania ciranosa, sp. iiov. 



Kig-. 19. A soiiitnvliat ili.storted upper valve ; showing tlie liiu-l.\ graimlose surface. 

 Fig. 20. A portion of the surface enlarged. X 20. 



Hamilton group. Centerfield, N. Y. 



Crania Tkentonensis. Hall. 



Figs. 21, 22. Fi-ont ami protile views of an upper valve. 



Trenton limestone. MiddlemUe, N. Y. 



Crania scario.sa, Htill. 



Fig. 23. A l)ra<-hial valve of Strophumena alteraata, covei-ed with shells of this species all of which can-y 

 the radiating and fine concenti'ic ornamentation of the host. 



Fig. 24. 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 adjnstors are discernible. In this .species as usually presei-ved the muscular im- 

 pressions appear as dark discolorations of the shell, indicating a probable greater density of 

 the shell-substance. X 2. 



Fig. 2.'). The interior of a lower valve. The poslerim- scars are more distant and smaller than in the 

 opposite valve, while the anterior scars are much larger. X 2. 



Fig. 26. A shell of PlatyMi-oplua lynx, having the surface of the brachial valve crowded with individuals 

 of this species. 



Hudson Ri\-ei- group. Cincinnati, Ohio. 



Crania .multipunctata, Miller (= Crunia scahiosu, Hall). 



Fig. 27. One of a group of in<lividnals attached to a fragment of Monticdlipor.\. The punctate surface 

 charac-ter of the host is impressed upon the shell, gi\-ingit a remote resemblance to the surface 

 of Tremalis Urminalif:. X 2. 



Hudson River group. Covinylon, Ky. 

 Fig. 28. Another specimen with similar surface mai-kings. X 2. 

 Hudson Ri\er gi-oup. Blanchester, Ohio. 



Crania .-^ocialis, Uliich {== Cranin .fmhioxa, Hall). 



Fig. 29. A fi-agment of a crinoid colunm, covered with individuals wdiich retain very liistinctly the impres- 

 sions of the sutures between the segments. X 3. 

 Hudson River group. Covington, Ky. 



Crania percarinata, Ulficli {== Cru)ii<i seiib/'osa, Hull). 



Fig. 30. An individual which has been attached to some species of PtEUROToMARi-i. X 3. 

 Fig. 31. Another specimen, which al.so bears the surface markings of some gastropod. X 3. 

 Hudson River group. Covington, Ky. 

 These figures are from Mr. Ulrtoh's tyjiical .sjiecimens. 



Crania, .sp. nov. ? 



Fig. 32. The interior of an upper val\e of a probably smooth species. X 2.. 

 Lower Helderlierg group. Near Clarks^nlte, N. Y. 



Crania favincoi.a, .sji. nov. 



Fig. 33. A lower valve, slightly broken alioat the poslei-ioi- mai-gin, but showing the very large posterior 

 i.inscular impressions, the deeply impre.ssed anteriors, with sharply elevated margins and 

 median fulcrum ; also, the radiating pallial .sinu.ses. The shell is attaclied to a .specimen of 

 F(n'o.^<itts pirwni, Davis. 



Hamilton group. Crab Orchard, Ky. 



Crania Leoni, Htill. 



Fig. 34. The interior of an upper valve ; showing, in addition to the posterior and anterioi' .'idductor scars, 



the taint impressions of the lu'achial muscles 

 Fig. ,35. The exteiior of an upper valve. 



Clienumg group. Li'oii, iV. Y. 



