208 INFERIOR OOLITE AMMONITES. 



distinguished by its more prominent carina, which is also hollow, except on the 

 body-chamber. 



Haug supposes^ that Ch^amm. fallaciosum is descended from the Middle Lias 

 species, Gramm. kurrianum (Oppel). Seeing that this species is more compressed, 

 and has a much thinner ventral area, this supposition is directly contrary to the 

 mode of development which seems to be the rule among other species. I prefer 

 to consider that Oramm. fallaciosmm is derived from Gramm. quadratum, and that 

 I do not know any species sufficiently evolute to be the parent of Gii^amm. 

 quadratum. 



The facts that in the adults of these forms the ventral area is becoming 

 thinner, and the ribs pass into fine stri^, point to the direction in which develop- 

 ment may be expected. It is, however, rather singular that both Gh-amm. 

 fallaciosum and its variety Cotteswoldise occur in the Striatulum-hQdi&, as well as in 

 the Dispansum-heds above (I have mentioned them in my sections under the name 

 " Gramm. radians, Wright," pp. 45, 46). Now, the other forms such as Gramm. 

 Ssemanni, &c. I have only found in the Dispansum-heds ; but, then, this may be due 

 to the fact that these forms are all so very much scarcer. 



Gramm. fallaciosum seems to be very local in its distribution. At particular 

 places it is certainly rather an abundant shell ; but good adult specimens are only 

 to be obtained with difficulty. The best locality is certainly Ooaley Wood, in the 

 Dispansum,-heds (page 45). I have also collected the species and its varieties at 

 Buckholt Wood, Cam Down, Stinchcombe, Wotton-under-Edge, Gloucestershire ; 

 and Mr. Hudleston has found it at Cranmore, Somerset. I have also small 

 specimens from Milhau, Aveyron (France). 



PI. XXXII, figs. 17 — 18, represent what may be considered as the typical 

 form of this species. PI. XXXIV, figs. 3, 4, show the var. Blngmanni with 

 broader ribs at intervals ; and fig. 5 is the suture-line. PI. XXXV, figs. 4, 5, give 

 two views of the var. Oottesivoldiae ; it lacks the test and the large hollow carina 

 from nearly all round the whorl. Fig. 6 shows the suture-line from both sides of 

 the whorl ; and it may be noticed that the siphonal lobe is situated to one side of 

 the keel-line, causing the sutures to be unsymmetrical. Fig. 7 is the front view of 

 the lobes and saddles taken from another specimen. PL XXXIV, figs. 10, 11, give 

 two views of a young specimen ; it is remarkable for the fineness of its ribbing 

 and for being very involute. In Plate A, figs. 39, 40, two examples of the 

 suture-line of this species are depicted ; fig. 40 is taken from a specimen which is 

 the older and more involute. 



» Op. cit., p. G16. 



