106 PSEUDOCERATITES OF THE CRETACEOUS. 
METASIGALOCERAS n. gen. Hyatt. 
The type of this genus, Metasigaloceras rusticum (Sow.), has been 
figured by several authors.* All of these figures, including Sowerby’s, 
show a form in section like that of Sigaloceras taylori and two rows of large 
tubercles. These are, however, not truncated on the casts as in that genus, 
but are apparently hollow spines arranged in two outer lines. There is no 
inner line of tubercles. There are the same number of lobes and saddles 
on the sides as in Sigaloceras, viz., three broad and rather deep, solid 
saddies with corresponding large lobes. The sutures, as figured by Sharpe, 
are sufficiently similar to those of other genera in the family Mantelli- 
ceratidz: to show that it can readily be placed in this group. The first 
lateral saddles have three long branches, the second lateral is rather narrow 
and, although well divided, is club shaped, and the third is broad and 
deeply bifid. This outline is more like that of Douvilleiceras than any other 
genus. The dorsal sutures could not be compared. The alternating costz 
are tuberculated on the venter of Pseudaspidoceras and smooth in Sigaloceras. 
The general resemblances to Aspidoceras are apparently close, but as this 
genus has no inner line of tubercles and perhaps no strongly developed 
lateral costations at any stage, the comparison fails. It is obviously a 
more primitive form than that of Pseudaspidoceras or Diadochoceras. 
PSEUDASPIDOCERAS n. gen. Hyatt. 
This genus is instituted for some Indian fossils which in the adult forms 
and ornaments of some species show close parallels with Jurassic Aspido- 
ceratidee, but the development and sutures place them in the same family 
with Diadochoceras. Their forms are discoidal with quadrate volutions, 
broad concave venters, flat lateral zones or sides, prominent umbilical 
shoulders, and distinct convex, smooth umbilical zones. The cost are 
wide apart, cross the venter and have two ventral and at least four lateral 
rows of tubercles, two on either side. The young have in the type form 
Pseudaspidoceras footeanum (Stoliczka),” stage similar to that of Diadochoceras 
nodosocostatum with, however, more prominent alternating costee and more 
quadragonal form of whorl. 
« Amm. rusticus Sowerby, Min. Conch., p. 177; Amm. rusticus d’Orbigny, 1840, Terr. Crétacé, 
pl. 111; Amm. rusticus Sharpe, 1856, Foss. Moll. of Chalk of England, pl. 20. 
5 Foss. Ceph. Cret. Southern India, pl. 52. 
