176 PHOLADIDA. 
times the usual size; its diameter greatly exceeds the anal 
one. There are on each side of the body a pair of long nar- 
row symmetrical branchiz; these are nearly of similar size, 
reaching fully to the anterior end, from which they taper 
gradually posteally, and le, not free, but fixed throughout 
their extent to within 4 an inch of the branchial compart- 
ment ; they are pale brown; the branchial vessels are trans- 
verse, large, but not crowded, and present the aspect of coarse 
pectinations. On each side of the body there is a pair of 
the palest bluish-white, large, subsymmetrical, fleshy, pointed 
palpi, representing very elongated triangles ; each pair is con- 
nected with its correspondent one by fillets above and below 
the mouth; they are strongly obliquely striated, as well as 
reticulated, though irregularly, on the imner surface by the 
vessels of the circulation; on the outer side the striz or reti- 
culations are not apparent. The branchiz at their anteal 
angles effect a contact with the palpi at their posteal points. 
The outer palpum of each pair appears rather less, and more 
laminar than its fellow. These appendages are usually con- 
sidered to be of a tentacular nature, to conduct the aliment 
into the mouth: they may be; but they have also branchial 
functions, as they are connected with each other by a very 
visible artery that coalesces with that of one of the main 
branchize, and I have not a doubt that leading branchial veins 
form a similar union with those of the regular branchie. 
The liver is anterior, of ample volume, granular, and yel- 
lowish-green. 
P. parva, Pennant. 
P. parva, Brit. Moll. i. p. 111, pl. 4. f. 1, 2. pl. 2. f. 2; (animal) pl. F, 
£3 & 3a. 
Animal thick, subcylindrical, less elongated than its con- 
geners; body milk-white; mantle pale bluish-white, when 
deprived of the fugacious light-red epidermis, which, at the 
closure of the valves, forms a line resembling a suture of a red 
sandy colour: this division of the body causes each side of it 
to appear banded. The mantle is closed except an aperture 
for the foot, and is prolonged into a long retractile sheath 
