PLATE 22 



Mendacella uberis (Billings) 



1. — Dorsal interior, showing cardinalia. 

 2. — Ventral interior, showing musculature. 

 3. — Dorsal internal mold, showing elongate Dalmanella- 

 like muscle field. 



Ordovician (Richmond, Ellis Bay), E. of Junction 



Cliff, Anticosti. Cat. No. 10415 Y. P. M. x 2. 

 8. — ^Ventral exterior. 



Silurian (Anticostian), Anticosti. Cat. No. S 1049. 



x2. 



Figs. Wattsella edgewoodensis (Savage) — Cont. 



13. — Ventral interior, showing flaring dental plates and 



heart-shaped muscle field. 

 22. — Dorsal interior of a silicified shell, showing remark- 

 ably long brachiophores (crura?). 

 27, 28. — Dorsal and ventral exteriors, to show ornamenta- 

 tion. 

 Silurian (Edgewood), Edgewood, Pike Co., Mis- 

 souri. Cat. Nos. S1075 (figs. 13, 27, 28), and 

 S 1083 (fig. 22). x2. 



Mendacella muUochiensis (Davidson) 

 4, 5. — Ventral internal mold (fig. 5), x 1.5, showing mus- 

 culature, and wax impression taken from it, x 2. 

 Silurian (lower Llandovery, Mulloch Hill), Mulloch 

 Hill, Girvan, Ayrshire, Scotland. Brit. Mus. Nat. 

 Hist. (fig. 5); Cat. No. S657 (fig. 4). 



Fascicostella sedgwicki (D'Archiac and Verneuil) 

 6. — Dorsal internal mold, showing adductor field like that 



of Parmortkis, see pi. 21, fig. 13. 

 7. — ^Ventral exterior, showing bundled costellae. 

 10. — Replica of interior. 

 11. — Dorsal interior, showing cardinalia. 

 16. — Reverse side of fig. 6, showing ventral interior mold. 

 Of significance is the septum extending forward from 

 the adductor track separating two pallial trunks. 

 Devonian, Vise, Belgium. Mus. Comp. Zool., Har- 

 vard Coll. X 2. 



Fascicostella gervillei (Def ranee) 

 12, 15. — Ventral and dorsal exteriors, showing fascicostel- 

 late exterior. 

 Devonian (Ffj), Koniepruss, Bohemia. Cat. No. 

 S925. xl.5. 



Fascicostella sp. 



3 1 .• — Large specimen, showing dorsal exterior. 



Devonian, Vise, Belgium. Mus. Comp. Zool., Har- 

 vard Coll. X 2. 



Wattsella edgewoodensis (Savage) 

 9, 23, 25, 29. — Several views to show dorsal interior. 



Fig. 



23 shows left brachiophore plate broken away to ob- 

 tain a clearer view of the right plate. Fig. 29 is an 

 enlargement of fig. 23, x 4. Fig. 2 5 shows socket and 

 fulcral plates. 

 Silurian (Edgewood), Edgewood, Pike Co., Mis- 

 souri. Cat. Nos. S 1078 (figs. 23, 25, 29), S 1079 

 (fig. 9). All except fig. 29 x 2. 



Wattsella testudinaria (Dalman) 



14, 19, 24. — Posterior, ventral, and dorsal exteriors, x 1.5. 

 21. — Dorsal interior, showing subparallel brachiophore 

 plates, meeting the median ridge, x 2. 



Silurian, Borenshult, Sweden. Riks. Pal. Zool. Avd. 



Stockholm. 



17. 



Wattsella wattsi Bancroft 



-Ventral exterior, a replica of the internal mold. 



18, 20. — Dorsal internal mold, and wax replica of it, show- 

 ing subparallel brachiophore plates meeting median 

 ridge. Cf. figs. 21, 9, and 23. 

 26. — Ventral internal mold, showing subcordate muscle 

 area. 

 Ordovician (Marshbrookian, W. wattsi zone), 

 Woolston, Horderley District, E. Shropshire, Eng- 

 land. Cat. Nos. S2128 (fig. 17), S2129 (figs. 

 18, 20), and S2130 (fig. 26). x 1.5. 



Horderleyella sp. 

 30. — Dorsal interior, showing fulcral plates outside brach- 

 iophore plates. 

 Ordovician (Marshbrookian, Wattsella zvattsi zone), 

 Marshbrook, N. of Horderley, E. Shropshire, Eng- 

 land, x 1.5. 



Horderleyella plicata Bancroft 



32. — Ventral internal mold. 

 33. — Wax replica of dorsal external mold. 

 34,35. — Dorsal internal mold (fig. 35) and wax replica 

 of it showing cardinalia. Brachiophore plates con- 

 vergent and supported by low lateral septa. 

 Ordovician (basal Caradocian, H. flicata zone), 

 Horderley, E. Shropshire, England. Cat. Nos. 

 S 21 32-21 34. x2. 



238 



