58 BULLETIN OF THE 
If this course of development really takes place, the various structures 
in the eye of an adult Argulus can be easily homologized with those 
in Amphipods. Thus the corneal hypodermis and corneal cuticula of 
Amphipods would probably be represented by the hypodermis and cu- 
ticula dorsal to the eye in Argulus (Fig. 11). The basement mem- 
brane of this hypodermis would correspond to the corneal component 
of the corneo-conal membrane of Amphipods, and the conal constituent 
would be represented by what is called the preconal membrane in Argu- 
lus (Fig. 11, mb. pr’con.). Proximally, the preconal membrane becomes 
continuous with the sheath of the optic nerve (Fig. 11, mb. x. opt.), 
the equivalent of the capsular membrane of Amphipods. The basement 
membrane of the retina in Argulus, as in Amphipods, is the membrane 
pierced by the fibres of the optic nerve (Fig. 11, md. ba.). 
Grobben (79, p. 258) has suggested that possibly the eye in Argulus 
is of the same type of structure as in Phyllopods, but I do not share 
in this opinion for the following reasons. In Estheria, the delicate 
cuticula which covers the optic stalk is morphologically a portion of 
the outer surface of the body, and, as I hope to show subsequently, is 
subtended by a true corneal hypodermis. There is no corneal hypo- 
dermis beneath the preconal membrane of Argulus. Moreover, there 
is nothing in the eye of Argulus to correspond to the optic pocket of 
the Estheride, or to the optic sac of the Cladocera, except the circum- 
retinal blood space, and it seems to me very improbable that this space 
was once a cavity in communication with the exterior, and afterwards 
became converted into a blood space. I therefore believe that the 
plan of the eye in Argulus is not similar to that in the Phyllopods, 
but rather that it represents a modification of the type presented by 
the Amphipods. The satisfactory determination of this question can 
be settled, however, only by embryological evidence. 
Eucopepoda. —In adult specimens of those true Copepods sheet 
possess rudiments of the lateral eyes, — the Pontellide and Coryceide, 
—the retina is apparently separated from the hypodermis. In the 
Coryceidee it usually lies at some considerable distance from the hypo- 
dermis, and in Pontella the two structures, although near one another, 
are nevertheless not continuous. 
The development of the lateral eyes in the Corycexide and Pontel- 
lidee has not been studied, and consequently it cannot be stated with 
certainty whether the retinas in these Crustaceans originate from the 
hypodermis or not. In the metanauplius larva of Cetochilus, a Copepod 
which as an adult has no lateral eyes, Grobben (’80, p. 262) has de- 
