MUSEUM OF COMPARATIVE ZOOLOGY. 69 
number of cells which cover the area of each cone is about twelve. A 
corneal hypodermis of this same character also occurs in Talorchestia, 
although in this instance the number of cells over a cone is only about 
nine. 
According to Watase (90, p. 295), in the species of Talorchestia 
which he studied there were only two cells in the corneal hypodermis 
opposite each cone, or, as he expresses it, under each facet. When com- 
pared with the results recorded in the preceding paragraph, this observa- 
tion appears somewhat striking, and the more so since two, the number of 
cells recorded, is the usual number found under each facet in other Crus- 
taceans. If Watase’s observation be correct, the relation which would 
thus be established between this Amphipod and other Crustaceans would 
be an interesting one. The desirability of confirming Watase’s observation 
must, therefore, be evident ; but unfortunately he has not given the name 
of the species of Talorchestia which he studied, and I have therefore 
not been able to verify his statement. In the only species of this ge- 
nus which I have examined, viz. T. longicornis, the arrangement of the 
cells in the corneal hypodermis is very different from that described 
by Watase. 
The conclusions which I draw from the preceding account are, that 
in the eyes of Amphipods a corneal hypodermis is present, and the cells 
composing it are usually not arranged with regularity. 
The peculiar bodies observed by Schmidt (’78, p. 5) in the membrane 
between the corneal hypodermis and the retina proper in Phronima, and 
considered by Claus (’79, Taf. VI. Figs. 48, 49, B. nw.) as nuclei, are 
apparently not represented in other Amphipods. Their significance is 
still a matter of doubt. 
The corneal cuticula in Amphipods has been described by almost all 
observers as unfacetted.t_ According to Della Valle (’88, p. 94), how- 
ever, in some of the Ampeliscide this cuticula is facetted, and Watase 
(790, p. 295) has also observed facets in Talorchestia. But with these 
two exceptions the corneal cuticula of Amphipods has been described 
1 An unfacetted corneal cuticula has been recorded in the following genera of 
Amphipods : Amphithoe (Milne-Edwards, ’34, p. 116); Caprella (Frey und Leuck- 
art, ’472, p. 103) ; Cyamus (Miiller, ’29, p. 58, Frey und Leuckart, ’47, p. 205) ; Gam- 
marus (Miller, ’29, p. 57, Frey und Leuckart, ’47, p. 205, Pagenstecher, ’61, p. 31, 
Sars, 67, p. 61, Leydig, ’78, p. 235, Grenacher, ’79, p. 109); Hyperia (Gegenbaur, 
’58, p. 82, Grenacher, 79, p. 111, Carriere, ’85, p. 160) ; Phronima (Pagenstecher, 
61, p. 31, Schmidt, ’78, p. 5, Claus, 79, p. 151); Talitrus (Grenacher, ’79, p. 109) ; 
and the Platyscelide (Claus, ’87, p. 15). I have observed an unfacetted corneal 
cuticula in Gammarus, Caprella, and Talorchestra longicornis. 
