PL A' IT. XXXVI. 

 Fig*, land 1 MoiMoi.or-i* SIMILIS Ulrleh ; 



(to* aU<> pin- xi.ii. HI:. l.i 



Dorsal and anterior view- of the original type of the specie*. Middle third of 

 the Trenton -h.ile*. Minneapolis, Minnesota. 



s. 3 to 6. Moi>i<n."p-i- Ainu i A. n. -j, 506 



3 an. I 4. The riirht -hie and a dorsal view of a pNid cast of the Interior. Middle third of 



the Trent<. n -hales, near Fountain, Minnesota. 

 5 and 6. A smaller test! ferous sjnvini,-n. iiujM-rfe.-t posteriorly, of the natural site and x2. 



Chat Held, Minnesota. 



7 M,.I>I s ANA, n. sp 607 



-:!. of .1 well preserved cast of the Interior Galena shale*. Cannon Falls, 



K; K ' 8. MOIH..I . p-i- MYMI."I:>K- Flail 608 



Cast of a left valve. M i<l<l!c Galena, near Wykoff, Minnesota. 



Fig*. 9 and 10. MODIOLOPSIH CHATH -. n. -i> 608 



IlikTht -i.le of a cast of the interior, of the natural size and x 2. Middle third of 

 i n-rrton shales, rii.mietd, Minnesota. 



Fig*. II and 12. M<'|>II>I.I>P-I- "IMOLHTA, n. sp 609 



Testlferous left valve, of the natural size and x 2. Upper part of the middle 

 third .,f the Ti.-titoii shales, Goodbue county, Minnesota. 



Fig*. 13 and 14. M<>I>X.I <>I-IH RXCRLLENS, n. sp 611 



l.'l. Cast of the Interior of a right valve. The specimen Is a little Imperfect In the 



anterior third. Geol. Survey Mus. Beg. No. 8374. 



14. Well preserved fragment (anterior part) of a cast of the Interior of a left valve. 

 Survey Mi. ~. UNI Keg. No. 8375. Hudson Blver group, Granger, Minnesota. 



Figs. 15 and 16. MOMOUWUI OOMQATA DlfiBh 608 



The specimen described, a testlferous right valve, of the natural size. 



16 and 16a. Lateral and dorsal views of same, x 2. Upper part of the middle third of the 

 Trenton shales, Goodbue county, Minnesota. 



Fig*. 17 and 18. WHITRAVRSIA SITBCARIMATA, n. sp 616 



The right side and an anttro-dorsal view of a cast of the Interior, showing the 

 f"r n of the shell and obscure trace* of radiating stria; on the posterior part. 

 Middle Galena, Goodhue county, Minnesota. 



Fig*. 19 and 20. WHITRAVRSIA MODIOLIFOKMIS Meek and Worthen 516 



19. left side of an Internal cast, Belolt, Wisconsin. Survey Mus. Beg. No. 8341. 



20. View of the original type of the species. In the drawing the base and the ante- 



rior end is restored and the right valve tilted, so as to give an exact dorsal 

 profile. "Lower Blue" beds of the Trenton formation, Mineral Point, Wis- 

 consin. Illinois State Museum. 



Fig*. 21 and 22. OOLTOMYA DUOSSA, n. sp 524 



The nearly perfect shell upon which this species is founded; of the natural sice 

 and x 4 5. Middle third of the Trenton shale*, Chatfield, Minnesota. 



Fig*. S3 and 24. ORTHODBSMA SUBNASUTUM Meek and Worthen 618 



Lateral and dorsal views of an entire cast of this specie*. Galena limestone, 

 \OD, Illinois. 



Fig*. 25 and 26. OHTHODESMA SCHUCHBKTI, n. sp 518 



ral and dorsal views of a cast of the Interior, which Is Imperfect posteriorly, 

 but In good condition otherwise. Middle Galena, Kill more county, Minnesota. 

 Sir .m Reg. No. 8343. 



Fig*. 27 an.! J- Kr I:\MYA PLAN \ 11 512 



27. Inter . as obtained In a gutta-percha Impression of a cast <>f 



the Interior. 



28. HI nire and anterior muscular scar of the left valve, magnified nearly two diam- 



eters. Trenton limestone, Minneapolis, Minnesota. 



Fig*. 28 and 30. MATIIKKI A KUOOSA Ulrleh 663 



Views of the exterior and Interior of a large right valve \'\>\-r part of the 

 middle third of the Trenton shales, Goodhue county, Minnesota. 



|.,TK 



