NATICA. 
261 
tte aperture is very large. Under certain conditions of preservation there is 
a tendency to form spiral lines. 
Most of the specimens in the Dogger are small ; but here and there one finds 
fragments of a large shell which present similar peculiarities. This makes me 
rather disposed to consider that the very large casts which occur in the 
Northampton Sand (see PI. XX, fig. 1) may be megalomorphs of NafAca canina. 
The tendency to a median keel is seen even better in the cast than in the shell. 
196. Natica, species or variety. Plate XX, fig. 10. 
Description : 
Spiral angle . . . .70°. 
Height of body-whorl to entire shell . . 65 : 100. 
Length ..... 30 — 35 mm. 
Shell Euspiroid, oval, length to width as 1’3 : 1, traces of an umbilical fissure. 
Whorls about seven, square-shouldered, and deeply canaliculate, smooth, and 
moderately convex. Body-whorl full, yet angular, and with a slight tendency to 
a median keel. Lines of growth wide and rugose. Aperture semilunar with a 
slight incrustation on the columellar lip, and some trace of umbilicus. 
Relations and Distribution . — This form constitutes a step in advance beyond 
the members of the adducta-grou]) in the narrowing of the spiral angle coupled 
with a slight relative increase in the height of the spire. It is also a narrower and 
more elegant form than Natica Dundriensis, next to be described. The propor- 
tions are not far from those of Natica Bajocensis, but it is of larger habit, and less 
compressed in the body-whorl than that species. It has some resemblance to 
Natica Grythea, Laube (non d’Orb.), Die Gasteropoden des Brannen Jura von 
Balin, p. 4, PI. I, fig. 6. 
Two specimens are known to me ; the one figured from the ParJdnsoni-'zone 
of Bradford Abbas, and another from the ParMnsoni-zone of Horton Hill. Casts 
which correspond fairly in size and appearance occur in the Glypeus-gvit of 
Rodborough and the Parhmsoni-zone of Aston and Notgrove. Those from the 
Glypeus-grit have been identified by Mr. Witchell as Natica Strichhmdi, Morris 
and Lycett. There are also some specimens in the Woodwardian Museum like 
these. Simply as a distinction I would call this Natica “ subelegans.” 
