244 
Miscellaneous. 
the Cephalopod of a choroid and of a vascular iris, and thence also 
of true ciliary processes, and admit, in the thickness of the retina, 
one layer of pigment. From a great number of preparations, 
obtained from eyes in which he injected the blood-vessels, the author 
demonstrated :—1. That in the Cephalopoda not only does a vascular 
choroid exist, but, especially in Sepia officinalis , that membrane in its 
three posterior fourths consists of three layers like that of Man and 
the Mammalia, and the middle one, as in these, is subdivided into 
two, a superficial one, formed of large arterial and venous vessels, and 
a deep-seated one, composed of a network of little arteries, veins, and 
capillaries (the Balkennetz of Hensen), in such a mannor as to form 
a true corio-capillary or Kuyschian membrane. 2. The iris is more¬ 
over well developed, rich in blood-vessels, and comprised, in part, in 
the so-called equatorial furrow of the lens. 3. The corpus ciliare 
is complete, and the ciliary processes more numerous and richer in 
vessels than those of most of the Mammalia. 
This existence of the iris, of the ciliary processes, and of the 
vascular choroid being demonstrated, the homology of the pai'ts of 
the organ of vision of the Cephalopoda with those of the eye in 
vertebrates, which is now-a-days accepted by all naturalists, is no 
longer admissible. Prof. Kichiardi passed in review the opinions 
expressed on the subject, and dwelt especially upon the memoir 
published by Hensen in 1865, from which he formulated the fol¬ 
lowing conclusions:—1. The part which that author regards as 
corresponding to the transparent cornea is only a fold of the skin, 
the margins of which overlap for a short distance without forming 
extensive adhesions in the Octopods, and in all those Decapods in 
which the tentacular arms are not entirely retractile but only in 
part (Oigopsidoc), whilst in the Miopsid Decapods they are soldered 
in such a manner as to form a lamina, against which the globe of 
the eye rests during the compression exerted upon it by the tenta¬ 
cular arm when this is retracted into the pouch which extends 
beneath the eye, and thus undergo less variation in their diameters. 
2. The cavity described as the anterior chamber is formed by the 
above-mentioned fold. 3. The membrane denominated argentea 
externa is the palpebral integument; and that considered as corre¬ 
sponding to the iris is the eyelid; whence the cavity regarded as the 
homologue of the posterior chamber is really that of the conjunc¬ 
tival sac. 4. The corpus epitheliale of Hensen is the true vascular 
ciliary body. 5. The so-called external or fibrous layer of the retina, 
which is produced into the ciliary body, is the choroid, upon the 
external surface of which radiate the nervous fibres arising from the 
ganglion of the optic nerve, which, in order to arrive at the so-called 
internal layer, or true retina, traverse its whole thickness, interpo¬ 
lated in small bundles among the blood-vessels, which, starting from 
the large superficial ones, run to its inner surface to form the corio- 
capillary network. 6. The pigmental layer, which is regarded as 
interposed between the two layers of the retina, is the true internal 
layer or pigment of the choroid.— Societa Toscana di Scienze 
Naturali, January 12, 1879. 
