TISSOTIID. 47 
the old-age characteristics are similar. Grossouvre’s fig. 2, also named 
robini, is apparently a distinct species. It has the subacute venter of the 
oldest gerontic substage of true robini when only 59 mm. in diameter, and 
this begins when the shell was about 40 mm. in diameter or earlier, accord- 
ing to this figure. This whole volution is also covered by dichotomous costae 
having only very faint tubercles. This might be a dwarf of this species, 
but is apparently not a young specimen. Redtenbacher’s figures (except 
perhaps 5, f and h) all appear to belong to this species, and fig. 5f may 
have been a worn specimen or a dwarf. At any rate, the latter has a 
suture with the first lateral saddles looking remarkably like an immature 
stage of those characteristic of robint. Grossouvre thinks this is the true 
ewaldi of Buch, but on the contrary it seems to me more likely that part of 
his ewaldi as given above belongs to robint. The peculiar ventral trend of 
the outer divisions of the first lateral saddles occurs apparently only in this 
species. Redtenbacher’s figures are of value in that they give information 
with regard to the young, showing that at a diameter of about 18 mm. the 
keel is prominent and continuous, as it is in later stages, the costee are well 
developed and uichotomous and have two rows of tubercles, one on each 
umbilical shoulder and a row on either side of the keel. It is also to be 
noted that the venter of this young specimen is more acute and the whole 
form more compressed than in the more mature stages. 
Locality: France and Austria. 
Age: Senonian. 
MeraTissoTiA Noposa n. sp. Hyatt. 
Tissotia haplophylla (pars) Grossouvre, 1893, Ammonites Craie supérieure, pl. 4, 
figs. 3, 4 (not fig. 5). 
The two specimens figured by Grossouvre have large nodes on the 
umbilical shoulders like those of haplophylla, but the costz are well 
developed at an age when these are absent in true haplophylla, as shown in 
Redtenbacher’s figure. The keel at the same stage is entire, whereas in 
haplophylla there is a row of tubercles. 
Locality: France. 
Age: Coniacian. 
