184 Prof. M‘Intosh’s Notes from the 
forms, this apparently has a very thiu cuticle, the cells and 
granules of the hypoderm almost reaching the surface. 
Marion and Bobretzky speak of a second operculum on 
another of the filaments. Their Apomatus assimilis differs 
in having ‘‘cystallins” on the branchial filaments, but 
perhaps this is only a variety of the above, which occasion- 
ally shows pigment-specks at the base of the branchia. A 
second small operculum is occasionally observed in those 
from the Channel Islands—arising, as in the case of the 
larger, from the tip of a branchial filament. 
The operculum is a soft globular enlargement on the end 
of a branchial filament, of the ordinary character as regards 
general structure and the presence of pinne. It consists 
of a layer of cuticle with a granular coat internally, and, 
moreover, the globe contains several branching filaments, 
resembling modified distal processes, which extend to the 
free end of the operculum. While thus serving as a plug 
to the aperture, the operculum would also appear to perform 
a respiratory function and it is filled with fluid. . The 
branchia bearing the operculum tapers little, and the pinne 
pass up to its termination. A constriction then occurs, 
followed by the slightly enlarged though short opercular 
pedicle, which is again slightly constricted at its junction 
with the operculum. In an example from St. Peter Port 
the operculum showed no branching filaments, so that this 
may be occasional or, perhaps, due to a parasitic growth. 
The body of the preserved animal is somewhat stout and 
short, the posterior region being especially massive, and it 
tapers ouly a little to the slightly flattened tail. The 
anterior region has a broad alar membrane, whilst the mid- 
dorsum is distinguished by a long conica] elevation with the 
apex directed forward and a median furrow, the rest of 
the dorsum being more or less convex, except in the 
instance where the hollows were filled with ova. The 
ventral surface is rather convex than flattened, but it has 
a median groove from end to end with the exception of the 
break at the alar fold. 
The collar-bristles form two conspicuous tufts, slanting 
obliquely forward and outward from a point a little in front 
of the bases of the first lateral tuft. They appear to have 
the same structure. 
The anterior region has six lateral setigerous processes on 
the ventral side of the alar membrane, and six elevated rows 
of hooks to their ventral edge. All the bristles are directed 
upward and backward, and have a uniform structure, viz., a 
straight shaft, narrowed at the insertion, then remaining 
