298 THE: CEPRALOPEDA 
Loligo, Sepia, ete., there are elongated cartilaginous lamellae at the 
bases of the fins. There is a nuchal cartilage at the base of the 
neck of all the Dibranchia in which the mantle is not fused to the 
head; consequently this cartilage is absent in Sepiola and the 
Octopoda (Fig. 264, D). It serves for the insertion of the lateral 
muscles of the funnel. Cartilaginous pieces also occur at the 
internal extremities of the retractor muscles of the head and funnel, 
and even in the two branchial laminae (Sepia). In the Decapoda 
there is sometimes a T-shaped basi-brachial cartilage at the bases 
of the arms on the anterior (dorsal) side of the head (Sepia, 
Fig. 264, C); it is united to the cranial cartilage and serves for the 
insertion of the brachial muscles. Finally, the ‘resisting apparatus ” 
Fig. 264. 
Cartilaginous skeleton of Cephalopoda. A, capito-pedal cartilage of Nautilus, ventral aspect. 
a, ridge which supports the pedal portion of the nerve-centre. , right-side view of the same ; 
the large anterior processes are sunk in the muscular substance of the funnel. C, cephalic 
cartilages of Sepia officinalis. D, nuchal cartilage of Sepia officinalis. (From Lankester, after 
Keferstein.) 
mentioned above is formed by sub-epithelial cartilaginous projections 
and depressions. 
It has been shown that Lepidoteuthis, a form not yet sufficiently 
well known, but apparently a member of the Oigopsida, is ex- 
ceptional in that the superficial portion of the integument gives 
rise to a layer of hard, projecting, regularly disposed, imbricated 
scales, lying above the chromatophores. In Octopus arborescens 
there are ramified and contractile tegumentary papillae. 
In several Dibranchia the integument contains certain so-called 
“aquiferous ” cavities, which open to the exterior by special pores, 
but have no communication with the circulatory system. In 
addition to the pockets of the tentacular arms of Decapoda, there 
are cephalic pores on the back of the head and at the base of the 
funnel in Ocythoé, and buccal pouches on the ventral side of the 
