104 PSEUDOCERATITES OF THE CRETACEOUS. 
diameter through the mesal plane and 20 mm. at the broadest part between 
the nodes. The next youngest volution is 9 mm. in ventrodorsal diameter 
and 9 mm. broad. 
BARROISICERAS Grossouvre.” 
According to Grossouvre’s and Redtenbacher’s figures this genus evi- 
dently has smooth, compressed young, with a continuous keel. Grossouvre 
shows some forms intermediate between those of his involute haberfellneri 
and the very discoidal ones figured by Redtenbacher. It is very obvious 
that these have no affinities with Tissotia, unless it may be through the 
similarity of the young. The young in this and in Tissotia suggests affinity 
with the so-called Oxynoticeras of the Cretaceous figured by Neumayer. 
Apparently the young figured by Redtenbacher is more involute than at 
later ages. 
The metamorphoses seem to be (1) entire keel, sides smooth, venter 
acute, and form involute; (2) costated with entire keel; (8) tuberculated 
and costated and keel broken up into tubercles by crossing of venter by 
costee; (4) continuous keel again. (See Redtenbacher, Am. Pion., Abhandl- 
K.-k. geol. Reichsanstalt, Vol. V, 1873, pl. 23, fig. 3b, d.) 
This group, so fully described by Grossouvre, contains an excellent 
series of forms which he largely includes under the single name of B. haber- 
fellneri. According to the mode of classification followed in these pages, the 
great differences in form and other characters, including corresponding differ- 
ences of development between his B. haberfelineri var. harlet and vay. des- 
moulinsi, indicate distinct species widely removed from each other. It 
makes no difference in following out this method whether these are 
obviously connected by intermediate forms or not, the sole criterion being 
whether the species differ in their form, involution, and other characters 
sufficiently to be arranged in a natural series which can be shown to be 
parallel or partly parallel with other generic groups about which there is 
more complete information. 
“This genus is referred to Mammitide in Hyatt’s chapter in Zittel’s Text-book, while in the 
original copy of the present manuscript, prepared in 1897, it appears among the Pulchelliidee. The 
notes on the Pulchelliidze then written are entirely superseded by the pages in Professor Hyatt’s hand- 
writing published here, in which the family is much restricted and does not contain Barroisiceras, 
Stoliczkaia, Tissotia, nor Neolobites, all of which were included in the original manuscript. These remarks 
x 
on Barroisiceras are inserted in the revised manuscript just before Pulchellidee.—T. W. 8. 
