GRAMMOCERAS FALLACIOSUM. 207 



Windungszunalinie, grossere Hochmundigkeit, convexe Seitenflachen, und durch 

 allmahliches Abfallen der Seiten nach der Externseite zu." 



Struckmanni. Denckmann gives only a side view of this form ; and it is not 

 at first easy to see wherein it differs from his form of Am. Ssemanni below (pi. iii, 

 fig. 2). However, he states (page 72) that Am. Struckmanni " in Querschnitt der 

 Windungen A^nm. Bingmanni . . am nachsten kommt, aber bedeutend schlanker 

 und nicht so hochmiindig ist, auch sehr langsam zunimmt." The correct identifica- 

 tion of this form must therefore depend altogether upon whether Am. Bingmanni 

 may have been correctly determined. Had it not been for this statement concerning 

 Struckmanni, I should have probably identified as Bingmanni the form I call 

 Cottesiooldise ; but Cotteswoldix is decidedly thinner than Struckmanni. 



As a further character of Struckmanni Denckmann says, " die Rippen werden 

 in Alter enorm breit." I do not find this to be quite correct. In adult forms 

 the ribs pass into very fine striae ; but just before doing so they are certainly 

 rather large. Yet, on the other hand, in the form I have identified as Bingmanni 

 the ribs are in places very broad, to show which the specimen depicted in PI. 

 XXXIV, fig. 3, has been selected ; and this character is not so pronounced in the 

 specimens I have identified as Am. Struckmanni. 



Denckmann states that Am. Struckmanni is nearest to Am. fallaciosum. I 

 should have thought Am. Bingmanni to be so. Denckmann does not say how 

 either differ from Bayle's species. 



Var. Gottesiooldias. The broad whorls causing a quick increase in diameter in 

 proportion to the turns — the small umbilicus — the compressed shape — these are the 

 characteristics of this form, which is a further development of Gramim. fallaciosum. 



Both Dumortier and Bayle have figured this form under the incorrect specific 

 name of Eseri. It does, certainly, on account of its involute, compressed shape, 

 bear some resemblance to this species of Haugia, but may be distinguished (1) by 

 its larger umbilicus which lacks a strong inner margin, (2) by its more distinct 

 ribs being much more strongly projected forwards on the ventral area. The latter 

 is the important feature, although the former is the more conspicuous. 



With Gramm. Gottesivohlise we seem to complete what may, in the absence of 

 any better term, be defined as an " ascending series." Gh-amm. quadratum, 

 Gramm. Ssemanni a, Gramm. Ssemanni /3, Gramm. Bingmanni, Gramm. fallaciosum, 

 Gramm. Cotteswoldix. With each form the turns become fewer, the whorls 

 broader and more compressed, the involution greater, the umbilicus smaller, and 

 the markings finer, in other words the development is normal (page 134). 



The form Gramm. Bingmanni is near to Ch'amm. Ssemanni [i ; but is more com- 

 pressed, and has a quicker-coiled umbilicus. Gramm. Struckmanni has an appear- 

 ance very similar to Gramm. doerntense, variety (PI. XXIX, figs. 8 — 10), but may be 



