Miscellaneous. 71 
about 103 inches long. The bone is moderately thick, slightly con- 
vex externally and concave within, thickened at the humeral articu- 
lation. The nearest approach to this coracoid is made by that of 
the skeleton referred to Hyleosaurus, from the Wealden of Tilgate ; 
but in it the distal portion of the bone is more prolonged, the median 
portion is less thickened, and the foramen is placed behind the 
middle of the humeral border, far away from the scapular margin, 
near which it is situated in the present bone. From the coracoid 
of Iguanodon it differs by the absence of the notch between the 
humeral and scapular surfaces, which there represents the foramen 
in this bone. In some respects it resembles certain American types, 
such as Morosaurus, and especially Camptonotus. 
MISCELLANEOUS. 
On the Unpaired Eye of the Orustacea. By M. Harzoe. 
Ir is well known that in most Crustacea, besides the two com- 
pound eyes (which are fused together in the Cladocera), there exists 
an unpaired median eye. It exists alone in most of the Copepoda 
and in the naupliiform larvee of all orders; it is even seen in the 
phyllosomatous larvee of the Loricate Decapods. Wherever the two 
kinds of eyes coexist in the adult but not in the newly-hatched 
larva, the unpaired eye is the first formed. It must therefore be 
regarded as the primitive eye of the Crustacea. 
The structure of this organ has not been sufficiently studied. 
Claus has demonstrated that it is formed in all cases of a central 
pigmented mass, in which are half immersed three lenticular bodies 
or “ crystalline spheres ”—two lateral, and one central. By investi- 
gating the anatomy of Cyclops and Diaptomus by the method of thin 
sections, I have ascertained that this organ is of a much more com- 
plicated composition than had been supposed. The pigmented mass 
is, so to speak, structureless ; the colouring-granules in it are espe- 
cially piaced at the surface contiguous to the ‘crystalline spheres.” 
Each sphere is composed of radiating elements or optical bacilli, the 
inner ends of which are applied against the pigmented mass, while 
the peripheral segments contain a nucleus. ‘The eye thus described 
is situated upon the terminal process of the brain, from which the 
optic nerves originate, one for each sphere; the nerve, instead of 
penetrating into the pigmented mass, skirts the outer surface of the 
crystalline sphere, and penetrates it directly not far from its hinder 
margin. 
Claus figured an analogous structure in the unpaired eye in the 
Phyllopoda (see his memoir on the development of Apus cancrifor- 
mis and Branchipus stagnalis); but he did not indicate its true sig- 
nificance. I have recently bred these same species, and have 
discovered in them a perfect analogy of structure with that just 
described in the Copepoda. 
