302 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
nerve-fibrils from the retina pass by means of tbe optic nerve into the 
cortical layer of the optic lobes ; here they penetrate into the plexiform 
layer, at the outer surface of which they expand into a bulbous structure. 
The author then describes in detail the histological structure of the 
cortex and medulla of the optic lobes, the description being illustrated 
by some beautiful figures. The general conclusion is that the retina of 
a Cephalopod corresponds to the layer of rods and cones in the Vertebrate 
retina, its individual cells being homologous only with the cones. The 
cortical layer of the optic lobes of a Cephaloj)od corresponds to the rest 
of the Vertebrate retina. This suggestion is only an application of that 
made long ago by H. Muller as to the dual nature of the Vertebrate 
retina, i.e. that it is comj)osed of a layer of epidermal sense-cells and 
numerous layers of nervous tissue. The separation of these two parts in 
the Cephalopod may seem to show that the optical organs of Cephalopod 
and Vertebrate are widely separated from one another, but the great 
similarity between the nerve-cells in the cortex of the optic lobes in the 
Cephalopod and the cells of the Vertebrate retina forbids this supposi- 
tion. For the details of the homologies of these cells reference must be 
made to the original paper, as also for the author’s hypotheses as to the 
paths of the nerve-impulses in the Cephalopod. The medulla of the 
optic lobes in the Cephalopod the author considers to be homologous 
with the optic lobes of Vertebrates. 
New Cephalopods.* — M. L. Joubin describes — so far as they are 
describable — some large Cephalopods ejected by, or found within, a 
sperm-whale ( Pliyseter macrocephalus) captured off the Azores on the 
Prince of Monaco’s expedition in 1895. Three specimens, over a yard 
long, indicated a new species of Histioteuthis ; a head, with arms as thick 
as a man’s, probably belonged to a species of Cucioteutliis ; but the most 
striking was a unique form— -for which the name Lepidoteutliis Grimaldii 
is proposed — covered with large rhomboidal scales in spiral rows. These 
scales were cartilaginous and transparent, and included very numerous 
clastic fibres and muscle-fibres. Their appearance suggested that of one 
of the Ganoid fishes. 
Lolig’o Pictet! and Idiosepius Picteti.f — Dr. L. Joubin notes that 
the singular little Cephalopod from Amboina, which he jmeviously 
named Loligo Picteti , really belongs to the genus Idiosepius Steenstrup. 
It closely resembles the only species of this genus hitherto known — 
Id. pygmseus Steenstrup — but Joubin remarks nine differences which 
warrant him in regarding it as a second species Id. Picteti. 
New Octopod.J — Dr. I. Ijima and Mr. S. Ikeda describe a new 
Octopod, which they include in the genus Opisthoteuthis Verrill as 0. 
deprcssa. The single specimen upon which the species is founded was 
obtained in Sagami Bay, at a depth of about 250 fathoms. The authors 
describe the external appearance and some points in the internal 
anatomy. 
* Comptes Rendus, cxxi. (1895) pp. 1172-4 (1 fig.), 
f Revue Suisse Zool., iii. (1895) pp. 459-60. 
% Journ. Coll. Sci. Imp. Univ. Japan, viii. (1895) pp. 323-37 (1 pi.). 
