Plate XVIII. 

 Protoconchs and Early Conch JVJwrls of Fusoid Shells. 

 (Drawn by Miss Elvira Wood, U. S. G. S., Washington DC, formerly 

 Instructor in Paleontology Massachusetts Institute of Technology.) 



(M C Z, Museum of Comparative Zoology, Cambridge, B. S., Museum 

 of Boston Society of Natural History; Acad. Sci., Museum of the Academy 

 of Natural Sciences, Philadelphia; Nat. Mus., National Museum, Smithsonian 

 Institution, Washington, D. C.) p^^^ 



Figs. I. Falsifusus ludovicianus. The apical whorls are imperfect, but of ^^ . 

 the F. meyeri type (Acad. Sci. 9488, X 16) ■ ■■■■■'■■ 



2. Falsifusus ? apkalis, showing the remarkably accelerated proto- 



conch (Acad. Sci. 6878, X 10) • • • • • • ; 



3. Levifusus ? mortoni, showing a protoconch similar to F^ meyeri 



The early conch whorls are rounded. Eocene (Acad. Sci. 68^5, 



4 cLluofusus'spiMy The 'protoconch and early whorls of the 

 conch Strong distant smooth riblets are shown on the f^nal por- 

 tion of the protoconch (Acad. Sci. 8024, X ^o) ■■••■••■•;••;- •; ^ 



5. Heilprinia caloosaensts. Protoconch and early conch whorls (Nat. ^^ 



Mus. 97494. X 16) ■ • • • • ' ' " " ■,' " „" 



6. Euthriofusus burdigalcnsis. The pseudofusoid protoconch (B. b. ^^ 



1400, X 10) ■,■■■■ ■..' ., ^ 



7 and 8 Clavilithcs deformis, showing the protoconch with the 

 trochoid apical whorls, characteristic of the British species of 

 Clavilithes. Barton Beds. (M. C. Z. 27783, X f ) 120 



(192) 



