TABLE OF CONTENTS 



PAGE 



TITLE PAGE, . x 



TABLE OF CONTENTS, 3 



INTRODUCTION 5 _ I2 



DISCUSSIONS OF THE SPECIES, I3 - 95 



CRANIA SILURIANA, Hall, I3 



ORTHIS ELEGANTULA, Dalman, ........ 13-17 



ORTHIS HYBRIDA, Sowerby, ........ 17-18 



STROPHOMENA RHOMBOIDALIS, Wilckens, .... . 18-22 



STREPTORHYNCHUS SUBPLANUM, Conrad, ...... 2 3~ 2 5 



STROPHONELLA STRIATA, Hall, . . . . . - . . 25-29 



STREPTIS WALDRONENSIS, Miller and Dyer, 30-31 



ElCHWALDIA RETICULATA, Hall, ........ 31-32 



ANASTROPHIA INTERNASCENS, Hall, ....... 32-34 



RHYNCHONELLA ACINJJS, Hall, 35-36 



RHYNCHONELLA NEGLECTA, Hall, ....... 37~39 



RHYNCHONELLA WHITII, Hall, 39-42 



RHYNCHONELLA INDIANENSIS, Hall, ....... 42-47 



RHYNCHOTRETA CUNEATA, (Dalman) var. AMERICANA, Hall, . . . 47-51 



ATRYPA RETICULARIS, Linnaeus, ....... Si-55 



RETZIA EVAX, Hall, .... 55-61 



RETZIA SOBRINA, sp. n., . . . . . . . . 61-64 



CCELOSPIRA DISPARILIS, Hall, ........ 64-67 



MERISTELLA RECTIROSTRA, Hall, 67-69 



MERISTINA NITIDA, Hall, . . . . ... . . . 70-72 



WHITFIELDIA MARIA, Hall, ........ 73~75 



SPIRIFER CRISPUS, Hisinger, . 75~77 



SPIRIFER CRISPUS, var. SIMPLEX, Hall, ...... 75~77 



SPIRIFER BICOSTATUS, (Vanuxem) var. PETILUS, Hall, . . . 75-77 



SPIRIFER RADIATUS, Sowerby, ........ 77~8i 



SUMMARY OF DEVELOPMENTAL CHANGES, 83-95 



PLATES AND EXPLANATIONS, . I-VIII 97 



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