Art. IX.] Herrick-Johnson, Geology of the Alhuquerque Sheet. 213 
from a specimen in which the spire has been partly abraded 
away but is otherwise apparently perfect. There are no teeth 
upon the inner lip. Upper layers of the Fox Hills near Una 
de Gato, east of the Sandia mountains. 
Cephalopoda. 
B acuities gracilis^ Shumard ? 
Our specimens agree with those doubtfully referred to B. 
ovatus by White and which have been identified as B. gracilis 
by Stanton. In the lowest fossiliferous horizon (gasteropod 
layer, in Rio Puerco valley). 
Baculites asper^ Morton ? 
A large species with distant nodes as in B. asper occurs in 
sandstone above the lignite east of San Francisco. 
Biichiceras swallovi, Shumard. hW "'■ , - 
Plate XXVII, Figs. 1-4. 
This beautiful species occurs in vast numbers in septaria 
concretions of the so-called cephalopod shales in the Rio Puerco 
valley where it is associated with Sphenodiscus lenticularis, 
Placenticeras placenta, Pholadomya subventricosa, and other 
lower Fox Hills species. The typical form as described by 
Shumard is abundant and is accompanied by a variety or possi- 
bly a distinct species characterized by the absence of nodes 
about the umbilicus, the greater lateral compression of the shell 
and the almost complete absence of the ribs. The paired dorsal 
nodes, though present, are inconspicuous. The sutural pattern 
is the same except that the serration of the lobes is less marked. 
Individuals with more prominent ribs and slight development of 
the umbilical nodes indicate the possibility of a transition to the 
type. The variety may be known as var. puercoensis. Plate 
XXVH, Figs. 3-4. It would seem that the two forms occur 
together wherever the species occurs. 
Sphenodiscus lenticidarCy Owen (sp). 
Not common in the septaria concretions of the cephalopod 
zone, Rio Puerco. 
