98 GASTEROPODA OF THE INFERIOR OOLITE. 
The above is in the main the original diagnosis of Morris and Lycett, which 
had to a certain extent been modified by Piette in 1856. To show the uncertainty 
which still prevails with regard to the family position of Brachytrema, I would 
refer to the partial list of genera, p. 12 of this Monograph. It will be seen that 
Fischer places the genus with a query under Cerithiide, Tryon places it under 
Littorinide or Cerithiide, Tate under Cerithudz provisionally, Stolicezka under 
Cerithiide. Morris and Lycett, on the other hand, originally regarded it as related 
to the Muricidee. 
These shells are very scarce and poorly preserved in the Inferior Oolite of 
England, so that our opportunities for adding to the knowledge we possess of the 
genus have not been great. Omitting the more fusiform shells which have 
occasionally been referred to Brachytrema, two distinct groups are apparent, one 
of which is like Purpuroidea in its aspect (B. Wrightii) ; the other might with 
more justice be regarded as related to the family of the Cerithiide (B. subvaricosum). 
Thus the genus is to be regarded as a composite one, which possibly may be 
broken up when the subject has been more fully ventilated. 
17. BracHyTREMA SUBVARICOSUM, sp. nov. Plate II, figs. 9 a, b. 
Description : 
Length ; ; : . 6°25 mm 
Width : 3 : ; . 412 mm. 
Length of body-whorl to entire shell, about - 90:2: 100 
Spiral angle ; 2 50° 
Shell small, subconical, apex pointed. Whorls six, nearly flat, and without 
strong sutural depressions. The ornaments consist of three stout, undulating 
spirals, which are wide apart, though somewhat fused together in the apical 
whorls. In the body-whorl a fourth spiral is developed; and in the base the 
spirals are fine and not numerous. The longitudinal ornamentation is irregular 
and not conspicuous, though slightly variciform in character. 
Aperture subquadrate and somewhat restricted, canal short, columella curved, 
notch narrow. 
Relations and Distribution —Brachytrema brevis, Piette (‘ Bull. Soc. Géol. 
France,’ 2me sér., vol. xiii, p. 564, pl. xv, figs. 21, 22), believed to be nearly 
the same as Turbo pygmeus, M. and L. (‘ Great Ool. Moll.,’ p. 65, pl. ix, fig. 29), 
approaches this species very closely. B. subvaricosum is less depressed, and the 
longitudinal ornamentation is less sharply developed; the spirals are larger, wider 
apart, and less numerous than in Vurbo pygmeus. B. varicosa, Lye. (‘ Suppl.,’ 
