=r) 
ARCAD 2. 
™“s 
The foot is hyaline azure, with a broad longitudinal medial 
line of intense snow-white, and a still intenser flake at the 
anterior end; it is fixed to the centre of the body by a mode- 
rately long pedicle; on first protrusion it takes a vertical 
position, and has a linguiform tapering aspect, but this part 
almost immediately, after feeling about, ranges itself anteriorly 
and horizontally ; end at the same time, on the other side of 
the pedicle, a bevelled, attenuated, pointed portion issues, 
somewhat shorter than the first; this is longitudmally cloven 
as far as the pedicle, and can form a sort of oval disk, but on 
the march it is rarely expanded: at the base of the cleft 1s 
the byssal gland, which cccasicnally pours out a glutinous 
red filamentous matter, that in confinement is copious, and 
discharged anteriorly, which at first I thought was fecal 
matters, and was puzzled to account for such an issue anteally, 
but the subsequent view of the single sessile posteal anal 
conduit and the ejection of pellets cleared up the difficulty. 
This foot is m every respect similar in miniature to that of 
the Pectunculus pilosus and of the Arcade, and m ne other 
bivalve family does the fcot exhibit a similar structure: this 
singular pedal characteristic of itself would sufficiently confirm 
the natural position of Lepton and Galeomina. 
The animal is vivacious, and allowed itself to be examined 
many times daily ; it marched with quickness, but I only cence 
saw It progressing in a vertical position; the usual posture of 
the shell is to rest on one cf the disks, which is frequently 
changed for the other; the adductors did not appear to allow 
of a greater opening of the valves than the ordinary extent. 
The animal, when placed at the bottom of a glass, always 
crawled up and moored itself by a filament at the side; some- 
times, however, it slipped its moormgs and floated free o t! 
surface of the water with the umbones downwards, and afte» 
an interval refixed itself by spmning a byssal thread. 
I cannot speak at present of the branchiz and palpi, as the 
animal and shell are in my collection, and are thus preserved 
to show that the shell, though usually described by concho- 
logists as gaping, can, m consequence of the flexibility of 
the thin laminar valves, be completely closed. There is no 
