120 Transactions of the Royal Society of South Africa. 
example of the species yet known. It is 290 mm. in diameter (nearly 11 J 
inches), and its greatest thickness 148 mm. ; there are indications of the 
former existence of at least another half whorl, so that the specimen when 
complete must have attained a very large size. The specimen is entirely 
septate, and the portion of the whorl that is missing was probably occupied 
by the body-chamber." 
" Another example (No. C 19418) is only 70 mm. in diameter, but is 
without doubt referable to the same species." 
" A third example (No. C 19419), in a somewhat harder and darker sand- 
stone, appears to be referable to this species. At first sight it seems to be 
more compressed, and to have less rapidly increasing whorls and a steeper 
umbilical wall than Pseud, indra, but these differences may in part be due 
to the imperfection of the anterior part of the outer whorl. Portions of 
the mouth-border are preserved on each side, and these show that the 
aperture was very oblique, the ventral (peripheral) portion being projected 
considerably forward. The body-chamber is seen to occupy rather more 
than one half of the outer whorl." 
Family DESMOCERATIDAE, Zittel. 
The genera Pachydiscus, Parapachy discus, Parapuzosia, Kossmaticeras, 
and the many allied developments discussed in the following pages can all 
be derived from Desmoceratid stocks that persisted during the Upper 
Cretaceous, and the unmodified types of which, owing to lack of exact 
information, are at present included in the genus Puzosia, Bayle, though 
the latter really should be restricted to the Upper Albian-Cenomanian 
planulata- group. Some of these Puzosid developments will be referred to 
below, under Puzosinae, a convenient but polyphyletic assemblage of 
successive waves of modified Phylloceratids ; but with regard to the 
Pachydiscinae, a sub-family that includes a number of developments of 
Puzosinae, the genus 
Pachydiscus, Zittel, 
is here taken to include only the group of P. peramplus, Mantell sp., as 
suggested by Kilian and Reboul * after Pervinquiere and other writers. 
Other species of this genus are : P. prosjperianus, d'Orbigny sp., P. lewesiensis, 
Mantell non Sharpe sp., P. catinus, Mantell sp., P. rhodanicus, Roman 
and Mazeran, P. juvencus, Laube and Bruder sp., P. vaju, Stoliczka sp., 
and probably P. seppenradensis, Landois. A. undatus, J. de C. Sowerby,f 
* " Les Cephalop. Neocret. des lies Seymour et Snow-Hill," Wiss. Ergebn. Schwed. 
Siidpol. Exp., iii, pt. vi, 1909, p. 41. 
t Min. Conch., vi, 1827, p. 134, pi. dlxix, fig. 2, B.M., No. 43940a. 
