SILURIC PAUNA FROM SOUTHERN MICHIGAN 549 



Gastropoda : 



38. Bormotonia suicarinaia Grabau manuscript ; most nearly related to Gotlandian 



species ; most characteristic of ttie Lucas. 



39. Holopea antiqua var. pervettista (Conrad;. 



■ 40. AcantJionema holopiformis Grabau manuscript, gen. et sp. ; a moderately high- 

 spired form like Orthonema, but with nodulated spirals. 



41. Strophostylus cyclostomus Hall ; rather common. 



42. Eotomaria areyi Clarke and Ruedemann ; rather common. 



43. Eotomaria sp. 



44. Lophospira hispiralis (Hall) ; rather common. 



45. Trochonema ovoides Grabau manuscript ; a large flat-spired form ; nearest ally 



in Helderbergian. 



46. Hercynella canadense Grabau manuscript ; the first species of this characteristic 



Hercynian gastropod found in America ; it is most nearly related to H. fasti- 

 giata Barrande. 



Cephalopoda : 



47. Dawsonoceras annalatum ; a strongly annulated variety. 



48. Cyrtoceras orodes Bill. ; identical with species described by Clarke and Ruede- 



mann from the Guclph. 



49. Poterioceras cf. satiriens Clarke and Ruedemann ; apparently identical with the 



Guelph species. 



50. Trochoceras anderdonensis Grabau manuscript ; a smooth-shelled and loose- 



spired form closely similar to T. priscum Barr. of the Bohemian Siluric. 



Annelida : 



51. Cornulites armatus Conr. ; a species also characteristic of the Guelph. 



TRILOBIT.S! : 



52. Prcetus crassimarginatus Hall ; several cephala and pygidia and a nearly entire 



specimen, indistinguishable from the characteristic Schoharie form. 



Q. Fauna of the Lucas dolomite. — This is exposed in the salt shaft and in 

 numerous quarries of southern Michigan and Lucas county, Ohio. 



Anthozoa : 



1. Eeliophrentis carinata Grabau manuscript ; rare in this horizon. 



2. Cylindrohelium profitndum Grabau manuscript, gen. et sp. ; in general like 



Diplophyllum, but with carinae ; calyx profound and parallel-sided. The 



most characteristic corals of this horizon, found also in corresponding hori- 

 zon of the Saskatchewan region, upper Canada. 



3. Cylindrohelium heliopliylloides Grabau manuscript ; more irregular and with 



shorter calyx, and with stronger carinated septa ; ss. ; an identical form fig- 

 ured by Clarke and Ruedemann as Heliophyllum sp. from the Guelph. 



4. Cladopora hifurcata Grabau manuscript ; not uncommon. 



Brachiopoda : 



5. Schuchertella interstriata (Hall) ; not uncommon. 



6. Gamarotcechia semipUcata (Conrad) ; a rather common species in the ss. 



7. Spirifer sulcata, mut. submersa Grabau; rare in the Lucas. 



8. Sp. modestus Hall ; not uncommon in the ss. 



9. Prosserella lucasi Grabau manuscript ; an abundant form with pronounced fold 



and sinus. 



10. Prosserella suhtrans versa Grabau manuscript ; a transverse form with plica- 



tions ; common. 



11. Prosserella tinilamellosus Grabau manuscript, with the dental lamellae united 



into a median septum at the base. 



12. P. planisinosus Grabau manuscript ; a large species with shallow, flat-bottomed 



but pronounced median depression ; rare. 



