58 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
preserved ; there are only very seanty traces of cell outlines and these princi- 
pally in the superficial division. The nuclei are distinct and rounded or oval 
and much more numerous in the superficial part. 
6. The Cover (co.) consists of a layer of scales which differ from any of 
those hitherto mentioned in form as well as in arrangement. They are 
greatly elongated and fusiform in outline, with one end blunter than the other. 
By this blunter extremity they are attached to the surface of the central mass 
and pass upwards from it ina more or less curved direction. Those which 
are furthest away from the stalk pass at an angle 45? to the surface. The 
next ones become successively more and more vertical and then begin to slope 
over to the other side. Those which cover the greater part of the central mass 
are inclined at an angle of about 30? to its surface, whilst at the stalk end they 
run almost directly into it. The thinner ends are drawn out into long deli- 
cate fibrils which curve round and become continuous with a limiting mem- 
brane forming the boundary of this layer. 
7. The Superficial Connective Tissue (s. c.) is a layer about 0.016 mm. in 
thickness. It may be divided into three parts, the deeper and the more super- 
ficial being structureless, whilst the middle one is granular. and has nuclei 
scattered at intervals along it. I have not been able to make out satisfactorily 
any nervous supply to the central mass in this instance, but it is quite possible 
that this may exist, between,the scales and the posterior cup as in other cases, 
for many of the sections were much broken. The Posterior Organ I have not 
examined in section. 
Regarding the functions and homologies of the different parts of these or- 
gans, there is but little that can be said. The central mass I take to be the 
source of light, and it agrees in position though not in structure with the cells 
to which Joubin (793, ’94,’95) has ascribed a similar function in Histioteuthis 
and Histiopsis. 
What I have termed the posterior cup appears to be closely similar to the 
corresponding part of the organ described by Joubin, and I think there can be 
little doubt that he is correct in regarding it as a reflector, though it is not ex- 
actly clear to me that one would naturally expect a body so constituted to 
discharge such a function. If this be admitted there would then be no reason 
for doubting that the superficial portions are a refracting apparatus. 
(B. Abraliopsis hoylei. 
(Plate 10, Figs. 1-10.) 
The luminous organs of this species are exceedingly numerous and are dis- 
tributed pretty freely over the ventral surface and to some extent over the 
sides of the mantle, head, and third and fourth pairs of arms, Their arrange- 
ment is almost exaetly bilaterally symmetrical with insignificant, variations 
here and there. Considered more in detail, the disposition on the various 
organs is a8 follows.: — 
