36 PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
its two robust branches on each side is almost as long as the first lateral 
lobe, which is irregularly tripartite and very broad at the base. The sec- 
ond lateral lobe is similar to the first, but very much smaller and more 
slender. There is only one well developed auxiliary lobe outside the 
umbilicus. (The details of the suture on the umbilical slopes have not 
been seen.) The siphonal saddle is oblong, rather broad, tripartite at 
the extremity and serrated on the sides in adult sutures. The other sad- 
dles are more or less distinctly bipartite but not symmetrically divided. 
The external and first lateral saddles have about the proportions of the 
first and second lateral lobes, respectively, and the second lateral saddle 
is relatively much broader and stouter than the first. The internal, or 
dorsal, portion of the suture has not been studied in the type species, but 
in H . argentinense the antisiphonal, or dorsal, lobe is slender, pointed and 
dentate and there are two rather simple, paired dorsal saddles of which 
the outer one is the broader. 
The type is Hatchericeras patagonense sp. nov., described below. 
The few ammonites collected by Mr. Hatcher in Patagonia have proved 
to be very interesting, and at the same time troublesome, in that they show 
features suggesting relationship with several described generic groups, 
while they do not possess all the essential characteristics of any one of 
them. It seems necessary, therefore, to state the facts, so far as they are 
determined, and to propose a new generic name for them. The forms 
thus grouped together, vary considerably in sculpture and general appear- 
ance, but in at least two of them, the type and H. argentinense , these 
differences are superficial only, and there is general agreement in all essen- 
tial features. The other two forms, each represented by a single small 
specimen, are placed here with some doubt, for reasons that will be given 
in connection with the specific descriptions. In the generic comparisons 
that follow, the data for Hatchericeras are taken from H. patagonense , 
unless otherwise stated. 
The adult in general form and surface has some resemblance to Haplo- 
ceras, but the sutures are very different in all their details. In its smooth 
adult whorls, the amount of involution, the form of the umbilicus and, to 
a less extent, the character of the suture, it suggests Ammonites clem 
d’Orbigny, which has been made the type of Cleoniceras by Parona and 
Bonarelli , 1 but is referred with the other members of the group to Desmo- 
1 Palseontographia Italica, Vol. II, 1896, p. 83. 
