A. E. Verrill — North American Cephalopods. 
339 
back of each eye-orbit. This cephalic sinus receives the blood from a 
large vein in the median line and near the inner surface of each arm. 
Numerous small veins from the head and eyes also enter this and the 
ophthalmic sinuses; others, entering the anterior vena-cava, from 
each side, along its course, come from the muscles of the head, neck 
and siphon, from the ink-sac, anterior part of the liver, etc. Two veins 
of considerable size, which become sacculated posteriorly, arise from 
the intestine and ink-sac and run back to the sacculated divisions of 
the vena-cava. A small vein also extends along the dorsal side of 
the efferent sperm-duct ( p ). Two large pallial veins, uniting together 
close to the branchial auricles, on each side, come from the sides of 
the mantle ( v , vc ') ; one of these (uc') runs from the anterior part 
backward, and receives a branch (fig. 1) from the gill; the other (u), 
from the middle and posterior parts forward. The posterior veme- 
cavte (vc") arise mostly in the caudal fins and posterio lateral portions 
of the mantle ; each one receives two large branches, one anterior and 
the other posterior, just at the point where it leaves the inner surface 
of the mantle. From this point they run forward parallel with the 
two posterior arteries, and converge to the region of the heart, where 
they join the great sacculated venous vessels (r) ; along a considerable 
portion of their course they expand and become large, elongated, fusi- 
form organs (/), probably renal in function, but much firmer, more 
definite in form, and finer in structure than the more anterior renal 
organs. 
The gills (g) are long, triquetral, acute, in section they are nearly 
triangular, with the free ventral sides convex, and the dorsal side flat 
or concave, except along the middle, where a thin median membrane 
(g) arises from the central stem and unites the gill to the inner surface 
of the mantle. The gills are composed of large numbers of thin, 
transverse branchial laminae, which extend outward symmetrically on 
each side from the large median blood vessels ( bo , bv ), each lamina 
having a long-ovate or crescent-shaped outline. A somewhat firm 
central axis or column gives support to the laminae and the large 
blood vessels. The great afferent vessel (fig. 1, bv) starts from the 
branchial auricle ( au ) and runs along the median-dorsal side of the 
gill, on the inner edge of the axial column ; a parallel vein (fig. 1), 
near the dorsal edge of the column, runs back and joins the lateral 
pallial vein (vc’). Each branchial leaf receives from the afferent 
vessel (bv), a branch which runs along the dorsal edge, giving off at 
regular intervals small, transverse, parallel branchlets, which in turn 
give off minute capillary vessels along their sides, and fade out near 
Trass. Conn. Acad., Vol. V. 42 Junk, 1881. 
