64b YORKSHIRE TYPE AMMONITES Oct. 



64. AMMONITES ANGUIFORMIS, Simpson 

 (Plate LXIV) 



Original Description 

 " 26. A[mmonites] anguiformis. [M. Simpson, 1843, p. 17.] 



[" I. Without a dorsal keel or furrow. 

 " a. No spines." p. 7.] 



" Depressed, volutions 5 or 6, exposed ; radii straight, very obtuse, 

 nearly obsolete on the back and inner whorls ; faintly striated ; aperture 

 circular ; diameter i ^l inch. 



" I have seen only one specimen of this shell, and am ignorant of 

 its locahty ; but I have little doubt that it is from the upper lias. It may 

 be placed near A. fimbriatus, though it differs materially from it in the 

 slenderness of the outer whorls. The shell has been partially removed, 

 and upon the cast, I see near the back, at the termination of the radii, 

 small flat places, as if a row of knobs had been rubbed off." 



Additional Details 



Simpson, 1855, 41, 42; p. 41, omits "Depressed"; for "faintly 

 striated " reads " transverse striae, irregular, faint." P. 42, for 2nd par. 

 " The inner whorls of this species are very slender and delicate, but the 

 outer whorl is rather coarse. Many specimens have a row of small 

 tubercles on the outer margin of the whorls, but this is not a constant 

 character. With a strong magnifier may be seen faint longitudinal 

 striae, in places merely fimbriating, or dotting the transverse striae." 



Simpson, 1884, 70, 71. At end of first par. has (p. 71) " L.L., 

 ironstone bands, R. H. Bay " ; near end of second, after " fimbriating " 

 omits the comma. 



Remarks 



Stages, conch, serpenticone ; periphery, i ; ornament, 5*, 

 The flat spaces noted by Simpson (1843) are the marks of the septa 

 which were at the bases of the spines. The inner whorls seem to have 

 been smooth up to about 16 mm. diameter .(cunctative palingenesis) ; 

 then are ribs and small tubercles ; while the outer whorls carry ribs and 

 irregular septituberculus marks. The specimen is poor. Its diameter 

 is i| inch (48 mm.). 



Genus, Deroceras, Hyatt, (Gen. iv) ; family Deroceratidas. 

 Geological position, probably L.L. y or z, unless it had been derived. 



Result 



Deroceras anguiforme, Simpson sp. 1843, Charmouthian, [armatum 

 zone], Robin Hood's Bay, near Whitby. 



