20 INFERIOR OOLITE AMMONITES. 



square with a less prominent keel as it gets larger), but it is too poor to figure. 

 I hope to be enabled to figure better specimens of both these varieties of L. 

 Murchisonce another time. 



Ludwigia cornu, 8. Buckman. Plate IV, figs. 1—4. 



1881 Ammonites subbadiatus, J. Buckman (non Sowerby). Quart. Journ. G-eol. 



Soc, vol. xxxvii, p. 61, fig. 2. 

 1881 Haepoceeas cobnu, S. Buckman. Quart. Journ. Geol. Soc, vol. xxxvii, 



p. 605. 

 1885 Hildoceeas (Ludwigia) coenit, U. Raug. Neues Jahrbuch fur Mineralogie, 



&c, Beil.-Bd. iii, p. 687, tab. 12, fig. 11. 



Discoid, much compressed, carinated, whorls flattened, ornamented with well- 

 marked reflexed bifurcating ribs. Ventral area plain, slightly sloping towards a 

 fairly prominent sharp keel. Inner margin concave. Inclusion variable, about 

 | to | of whorl; centre shallow, regularly coiled, with numerous rather coarse 

 ribs. Termination of body-chamber has long lateral lappets (most probably not 

 increasing in breadth at the end), and is produced and pointed on ventral area. 



This species is only variable to a very slight extent, the specimens with the 

 larger umbilicus having rather coarser ornamentation than the others. From the 

 preceding species, this one differs considerably, being more compressed, with a 

 sharper, more angular keel. Its suture lines are the same as those of Ludwigia 

 Murchisonce ; if anything, more simple. This seems to have been a small species as 

 I have never seen a specimen much larger than those figured in the plate. It is not 

 uncommon with more or less of the terminal lappets preserved, and on account of 

 them was -always formerly quoted from the Bradford Abbas district under the 

 name of Ammonites subradiatus, Sow. (to which species it bears no other resem- 

 blance), until I corrected the mistake and gave it the name of " cornu" on account 

 of these lappets. This species occurs in the Sowerbyi-zone at Bradford Abbas 

 and other quarries in the neighbourhood where the zone is exposed, and it is not 

 uncommon. It is associated with Lioceras concavum (Sow.), and several other 

 species of that group, and is probably not unfrequently confounded with the 

 common L. concavum. 



Plate IV, figs. 1 — 4, show the two forms of this species, and give a back 

 and front view. The keel of fig. 2 is hardly prominent enough, owing to absence 

 of test in many places. The flatness of the side view of fig. 1 seems to me 

 not quite sufficiently brought out. 



