85 
known by possessing an enormous number of luminous organs ”’ 
in the regular arrangement which he describes. In the new 
and much larger species from South African waters there is 
an apparatus so closely answering in its distribution to the 
luminous organs of S. challengeri that its function must almost 
certainly be the same. That the formation of the organs is 
the same in both species is probable, though I cannot pretend 
to have made out the series of lenses and layers which Hansen 
figures for the intimate structure. He mentions a chitinous, 
large, and very thick biconvex lens, the inner side of which 
is covered by a somewhat thinner concavo-convex lens. 
Behind this is found a thick layer of glandular cells, light 
greyish, very large, and most of them elongate, radiating 
towards the centre of the outer lens. ‘ The diameter of this 
layer,” he adds, ‘‘is somewhat larger than that of the inner 
lens, and when the luminous organs are examined in their 
natural position with a strong pocket-lens, this layer can often 
be seen through the skin as a whitish ring around the lens.” 
In the South African species the large and more or less elongate 
radiating cells are not greyish but red in the specimens figured, 
though other specimens show that this tint is at length evan- 
escent like the rest of the animal’s colouring (in formalin). 
The whitish ring is conspicuous against an opaque background, 
but not visible by transmitted light. The organs are here 
found in all the positions enumerated by Hansen, but there 
are many in addition, not only on parts which were missing 
from the mutilated “Challenger” specimen, but more par- 
ticularly elsewhere. Thus on the carapace, besides the row 
of four which is here increased to seven on the upper border 
of the branchial cavity, near the lower border there is a row 
of eighteen, there are two in an advanced position, and a 
large single one adjoining the little blunt keel which represents 
the hepatic spine. The sixth segment of the pleon has a 
lateral row of seven, the front one much the largest. There 
is one on the under side of the eye, in the concavity of the 
corneal margin. In addition to the one on the under side 
of the third joint, the first antennae have four on the first 
joint. The scale of the second antennae exhibits eleven 
instead of four. There do not appear to be any on the first 
maxillae, as is also the case in the other species, but on the 
second maxillae there are at least two on the vibratory lamina. 
The outer ramus of the uropod has a longitudinal interrupted 
row of nine, while the other species has only two in this position. 
The carinate rostrum is very like that described by Hansen 
for S. prehensilis, but it is horizontal. At the base of the 
spiniform apex the place for a dorsal denticle is barely indicated. 
B. 649. F 
