Co TRANSACTIONS OF THE WAGNER FREE 



time exclude Caricella. Nevertheless, the latter forms a convenient group 

 from which the typical Scapliella is separated, in most cases, by its more fusi- 

 form shape, more cancellated early whorls, wider canal anteriorly, and less 

 arched middle outer lip. In the type (recent) of Scaphella the nucleus has no 

 elevated point, but the Pliocene forms of the genus make a transition toward 

 Caricella in this respect. The plaits of Scaphella are flatter and, in harmony 

 with its more fusiform shape, generally more anterior and more oblique. 



Scaphella begins in the Eocene with such species as S. Showalteri Aldrich, 

 which are intermediate between Scaphella and Aurinia. This line is taken up 

 in the Miocene by 5. solitaria Conrad, which has the same color-pattern as 5. 

 jiinonia. In the upper (Miocene) bed at Alum Bluff, Fla., occurs the first 

 typical Scaphella, S. TrenholmiiT. & H,, followed by S.floridana Heilprin, in 

 the American, and 5. Lainberti Sby., in the European Pliocene, and the well- 

 known S.junonia of the existing epoch. 



Subgenus Aurinia H. & A. Adams, 1853. 



Plate 7, figures 2, 4, 5, 7. 

 Voluiifusiis Conrad, 1862. 



Aurinia Dall, Blake Gastr., Bull. Mus. Comp. Zool. xviii. p. 147, 18S9. 

 Type Aurinia dubia Broderip, Florida reef=. 



This group is separated from Caricella and the typical section of the genus 

 Scrt/i/ifZ/^ by the small number and eventual obsolescence of its columellar 

 plaits. It seems also to have lost its radula and jaw, and the recent species 

 offer a parallel in the general senility of several of its characters, compared 

 with its fossil ancestiy, with the senile degeneration described by Hyatt in 

 certain Ammonites. The young shell, with sharp plaits and distinct sculpture 

 recalls the Eocene Caricella and Voliitocorbis ; the adult, with its nearly 

 smooth surface and obsolete plaits, exemplifies the loss of emphasis commonly 

 associated with old age. 



In the Miocene we have Aurinia viittabilis Conrad (sp.) ; A. virginiana 

 Conrad (MS.), which is the same as A. typiis Conrad (which name must be 

 changed, as it is not the type or even typical) ; A. diibia Broderip, A. obtusa 

 Emmons (sp.) ; and an undescribed species with nineteen exceptionally strong 

 ribs on the upper whorls, fine spiral striation and four plaits on the pillar. 



A. dubia (PI. 7, figure 4) may be known by its thin shell, very straight pil- 

 lar, and two obsolete plaits when adult. 



A. mutabilis has a nearly straight pillar, two plaits and a small though char- 

 acteristic nucleus. It grows larger than A. dubia, and is often very like it, but 

 exhibits a perplexing tendency to vaiy. Conrad's figure of the type shows a 

 series of small riblets at the suture on the upper whorls. 



A. obtusa Emmons (PI. 7, fig. 7) has two plaits and a wide, very large nu- 

 cleus. It is evidently distinct from the preceding, but is so far only known 

 from young shells. 



A. virginiana Conrad. I find this manuscript name of Conrad's applying 



