22 
THE VOYAGE OF H.M.S. CHALLENGER. 
the extremity of a slight conical papilla in Spirula peronii (PL III. an.), whilst it is 
completely sessile in Spirula reticulata (Fig. R, viii). This anal opening has no filiform 
appendages, such as are found in other Dibranchiate Cephalopods. The intestine 
presents internally a longitudinal furrow bounded by two very distinct folds, as in all 
Cephalopods examined in this respect (Fig. 0, i). 1 
The little ink bag is situated ventrally (PL IIP, ik.) in the bend formed by the 
intestine (Fig. R, iii); it opens into the intestine quite close to the anus. 
IV. Circulatory System. 
The heart is situated in the viscero-pericardial cavity towards the ventral aspect, in 
front of the spire of the shell and under the intestine and the kidneys (PL VI. fig. 8). 
Fig. 0.—Transverse section of tlie in¬ 
testine of Sepia; x 18. i, longi¬ 
tudinal furrow; ii, intestinal epi¬ 
thelium. 
Fig. P.—Heart of Spirula reticulata, ventral view ; 
x 4. i, right auricle ; ii, ventricle; iii, pos¬ 
terior aorta ; iv, posterior pallial artery ; v, 
recurrent (genital) artery ; vi, left branehio- 
cardiac vessel (auricle); vii, anterior aorta. 
It is (especially in the individual of Spirula reticulata examined) very flat dorso- 
ventrally and asymmetric (Fig. P) ; the ventricle is almost entirely placed at the right of 
the median line, while at the left is found only one prominence towards the branchio-cardiac 
vessel or auricle. 
p Ornmatostrephes, Sepiola, Sepia, Octopus, Nautilus. A similar furrow has been met with in other 
Molluscs, as in certain Rhipidoglossids (example, Troclius). But in the initial portions of the intestine of 
Molluscs there is a corresponding longitudinal cushion (typhlosolis): e.g., in all the Lamellibranchs examined from 
this point of view ( Anodonta , Anomia, Donax, Ostrea), and the Gastropods, including the Pteropods ( Paludina, 
Helix, Auricula, Tritonia, AEolis, Acteeon, ZAmacina, Clio), and Chiton among the Amphineura. In all these 
animals, the intestine being much rolled up, it is difficult to determine the morphological position of this typhlosolis, 
but in the Cephalopods, where the intestine is only turned back and not twisted, we can see that the 
furrowed typhlosolis occupies the dorsal side, as is the case also for the organ of the same name known in 
the Oligochgetse. It is then probable that the dorsal ciliated furrow of the intestine of Neomeniidas also 
corresponds to it. 
