TURRITELLA. 
233 
170. TtJERiTELLA {Mathilda) strangulata, sp. nov. Plate XVII, fig. 5. 
Description : 
Spiral angle . . . . .12°. 
Height of whorl to width . . .1:1. 
Approximate length . . . .65 mm. 
Shell elongate, strongly tnrrited, deeply sulcated, sutnral angle very oblique. 
The whorls (about fifteen) are long and irregularly bulging, the principal promi- 
nence being posterior, where also is situated the principal spiral or carina. The 
spirals are six and sometimes seven in number, the third being the most promi- 
nent. Cross-hatching is conspicuous throughout the shell, the lines being nearly 
parallel to the axis, and fairly close. Other indications wanting. 
Relations and Distribution. — This species is distinguished from Turritella abbas 
by the width and depth of the sutural sulci, which, in conjunction with the 
excessive postero-mesial bulge of the whorls, give a curious strangulated appear- 
ance to the spire ; the ornamentation also is coarser than in T. abbas. As regards 
the outline of the spire, T. strangulata has considerable resemblance to T. 
Eartmanniana, Miinst. (Goldf. iii, p. 98, pi. cxcvi, fig. 8, a fossil of the Lias). But, 
to judge from the enlargement of Munster’s species, the ornamentation differs 
considerably. 
Note on the opalina-grou-p. From Turritella, eucycla, Heb. and Desl., and from 
T. Clapensis, Terquem and Jourdy, the members of this group are separated by 
the greater number of spirals in the whorls. Both the last-named fossils are 
more nearly related to T. quadrivittata, Phil. 
171. Turritella {Mathilda) quadrivittata, Phillips, 1829. Plate XVII, fig. 6. 
1829 and 1835. 
1850. 
1884. 
Tueeitella qtjadeitittata, Phillips. Gfeol. Torks., pt. 1, p. 129, pi. xi, 
fig. 23. 
Ceeithitjm quadeitittatum, d'Orhigny. Prod, i, p. 271. 
Tueeitella quadeiyittata, Phillips. Hudleston, Geol. Mag., dee. 3, 
vol. i, p. 202, pi. vii, figs. 11 
—13. 
Bibliography, ^c. — Without multiplying references it may be sufficient to state 
that authors have differed greatly as to whether Phillips’ species should be re- 
garded as a Gerithium or a Turritella. Morris, in his ‘ Catalogue,’ enters it under 
30 
