CLASS I.—CEPHALOPODA. 
ORDER J.—DIBRANCHIATA. 
Famity IIlJ.—TEUTHIDA. 
PHYLLOTEUTHIS, Meek and Hayden. 
Type, P. suboyatus. Cretaceous. Nebraska. 
Pen corneous, thin, subovate, slightly concave below, and 
convex above. From behind the mid- 
dle it narrows towards the front, the 
outiine of the lateral margins being 
conyex, while the posterior end is more 
or less obtusely angular. Apparently 
related to Beloteuthis and Teudopsis. 
(See p. 168.) 
FAamity ITV.—BELEMNITIDA.* 
The Shell of Belemnites consists 
fundamentally of :— 
1. A hollow cone, the phragmocone, 
Fig. 1, », with a thin shelly wall, 
termed the conotheca, c, and which is 
divided by transverse septa, concave 
above and convex below, into cham- 
bers or loculi; the septa are perforated 
nearthe ventral margin bya siphuncle. 
2. A guard or rostrum, g, more or 
less extensively enveloping the apical 
part of the phragmocone. ‘‘ The 
phragmocone is not a chambered 
body made to fit into a conical hollow 
preyiously formed in the rostrum, 
as some haye conjectured, but both 
rostrum and cone grew together; the 
former was formed on the exterior of 
a secretive surface, and the latter on 
the interior of another secretive sur- 
face.” (Phillips.) 
The rostrum is composed of calca- Fig. 1. 
reous matter arranged in fibres per- 
pendicularly to the planes of the laminew of growth. Pro- 
* See p. 173. 
B2 3 
Dorsal aspect. 
Ventral aspect, 
