VOL. XX. (3) 
DIBRANCHIATE CEPHALOPODA 
251 
straight well-defined bands dividing its surface into a triangular 
median area which broadens anteriorly, and bears a median, 
narrow filiform keel, and on each side a finlike expansion, 
having a convex outer boundary and extending along a con- 
siderable portion of the length of the gladius. The lateral 
bands are ornamented with transverse backwardly-bent lines ; 
whilst each lateral expansion, which extends almost to the 
anterior end of the gladius, is ornamented with fine oblique 
striae. 
Geoteuthis agassizii, Deslongchamps. 
In the present specimen the posterior end of the gladius 
is wanting ; the fossil, which is now 235 mm. long, probably 
originally attained a length of at least 290 mm. Only frag- 
ments of the actual gladius are preserved, but the form of the 
greater part of it is indicated as an impression on the surface 
of the slab. The anterior end of the gladius is broadly convex 
and about 50 mm. wide ; the thickened lateral bands limiting 
the median area are indicated by shallow depressions, which 
are here each about 4 mm. wide ; they do not appear to have 
been continued around the anterior border of the gladius ; 
posteriorly they converge at an angle of about 20°. They do 
not exhibit any curved transverse lines, and therefore closely 
resemble the corresponding bands in the gladius of Pterioteuthis 
and Leptoteuthis. The median keel, also indicated by a shallow 
groove, extends nearly if not quite to the anterior border 
of the gladius ; it appears to have been relatively feeble over 
the greater part of the length of the specimen, in fact some 
fragments near the posterior end of the gladius exhibiting 
the dorsal surface of the structure appear to lack any definite 
median keel. The impression also shows that the whole 
of the inner or ventral surface of the anterior part of the gladius 
was covered with very fine straight longitudinal striae. The 
lateral expansions extend from the posterior end of the gladius 
to within a short distance (apparently about 20 mm.) of its 
anterior end ; each attains its greatest width (about 38 mm.) 
at about 160 mm. from the anterior border, and as shown 
by the impression each was traversed by several obscure 
