HOYLE: REPORTS ON THE CEPHALOPODA. 57 
its deeper surface. It consists of a single layer of cells each with a definite 
rounded nucleus, ep. The pigment is of the reddish-brown character, which has 
already been described in speaking of the siphonal and ocular organs and 
appears to be contained in the inner portion of the cells (p. /.) 
IV. Tus ABDOMINAL Organs (Plate 9, Fig. 1, 41, 42) are two in number. 
The anterior (A!) occupies the position of the three organs in P, margaritifera 
(Hoyle, :02, Fig. 1, A 1, 2, 2), though it is proportionately not quite so far 
in front of the branchial organs as it is in that species. The posterior one 
(Fig. 1, 42) corresponds in position with that marked A 4 in the figure of P. 
margaritifera just cited. 
The anterior organ is slightly elliptical in a superficial view with the longer 
axis transversely ; its axes measure 0.6 and 0.4 mm. respectively. The organ 
is nearly hemispherical (or more accurately hemi-ellipsoidal) embedded in the 
tissues, with its flat surface outwards and on the same level as the abdominal 
zall. On the anterior aspect a kind of thread or stalk runs from it, em- 
bedded in the tissues. One organ which I removed was cut into sections 
longitudinally, that is, by planes parallel to the sagittal plane of. the body 
(Fig. 12) ; an examination of these showed it to be composed of the following 
structures ; — 
1. The Capsule. 
2. The Pigment Layer. 
3. The Cup. 
4, The Inner Cone. 
5. The Central Mass. 
6. The Cover. 
7. The Superficial Connective Tissue. 
1. The Capsule of connective tissue (c.) covers the whole of the hemispherical 
surface of the organ; it is very thin (about 0.08 mm. thick) and almost 
structureless, though delicate fibres can be traced here and there, and a few 
nuclei are scattered in it. 
2. The Pigment Layer (p.) immediately within the connective tissue just 
mentioned is thickest just opposite to the stalk and made up of reddish-brown 
granules like the similar layers in the other organs. 
3. The Cup (p. c.) is made up of scales, so far as can be made out closely 
resembling those already deseribed in other organs. The only sections I have 
of this organ are so deeply stained with braziline that it is impossible to make 
out any structure in them, This coat ig on average 0.1 mm. thick, 
4. The Inner Cone (i. c.) can be made out distinctly only on that side of the 
organ turned towards the stalk. It consists as in other cases of thin wavy 
fibres very deeply stained. It is much thinner and less conspicuous in this 
instance than in the others. 
5. The Central Mass (c. m.) is much less regular in shape than in those cases 
already deseribed, but shows traces of a constriction indicating a division into 
a deeper portion and a more superficial corresponding respectively to the sphe- 
roidal and conical portions of other cases. The minute structure is very badly 
