24 AET. 2. — H. YABE : CRETACEOUS 



the latter portion surrounding the earlier one. Such double 

 coils of a tubular shell around the same axis of volution, but 

 in opposite directions, may be either accidental, or due to the 

 animal itself having an inherent power of producing such coils. 



(4.) Again, there are some species of the later Cretaceous 

 which are remarkable in exhibiting a great range of individual 

 variations on the mode of coiling the shell. The variations,, 

 however, are due to a loss of power in the animal, which as it 

 grows no longer maintains its normal mode of coiling. 



In the present species, in spite of its being represented bv 

 a single specimen, the mode of coiling the whorls can neither 

 be accidental nor due to a loss of power to produce the regular- 

 ly wounded shell, as it is too regular to admit any such sup- 

 position. That it is a Turrilites or some allied genus which has 

 modified its mode of growth on account of its advanced age is 

 also inconceivable. Therefore, this formation of several U-shaped 

 curves must be ascribed to the inherent power of the animal. 

 It is for these reasons that the writer proposes to give a new 

 generic name to this single specimen. 



As above mentioned, this species has both suture and sculp- 

 ture which indicate its derivation from some species of Hetero- 

 ceras (?), e.g., Jleteroceras (?) Otsidcai in turreted groups of Am- 

 monites. From the form of the shell, we can readily see that 

 the animal led neither a free swimming life nor a sessile one,, 

 but was a creeper on the sea-bottom as is the generally accepted 

 view of Turrilites. 



QuENSTEDT after describing 2\trrilUes reßexas — an extra- 

 ordinary form of a doubly coiled shell, says:'* 



" Es mag wahrscheinlich Formen gehen, ^vo sich dieses hin- 



1) Qüenstkdt: I.e. p. oCG. 



