170 PECTINIDA. 
re-entering angle obtuse; nacre silvery white, margin pale greenish or 
ochreous; no perceptible cardinal tubercle, and with a short lateral 
ridge simulating a tooth (Gould). 
Length and height, 2# inches. 
A. fucata, Gould, U.S. Ex. Ep. p. 441, f 551. Shell obliquely 
ovate, surface with short loose laminze ; color radiated yellowish and 
rose- red, shining ; dorsal edge produced into a short acute wing, exter- 
nally forming a right angle, then sweeping backwards ; anterior forming 
an acute angle and sweeping forwards forms the obliquely ovate outline; 
auricle long, triangular, finely and loosely laminated ; re-entering angle 
aright angle, edge sharp and simple; nacre silvery white, becoming 
violaceous at the edge; cardinal tooth of left valve very strongly 
developed, inflexed ; lateral tooth short, delicate, bifurcate in right valve. 
Length, 24 inches; height, 2} inches. (Gould.) 
In his ‘‘ Expedition Shells” Gould says that this species comes from 
Fiji, but in the U.S. Ex. Ep. he says it comes from New Zealand. 
ORDER—MONOMYA. 
One adductor only ; ligament nearly internal; mantle uniforal ; hinge 
nearly or quite toothless, with one circumpallial nerve ; no pallial sinus, 
nor siphon. Shell generally inequivalve. 
FAMILY—PECTINID~. 
Mouth surrounded by foliaceous leaflets; labial palps truncated, 
smooth externally, pectinated within. Mantle freely open, the margins 
double, the inner pene en bearing fringes of tentacular filaments, and at 
its base a row of ocelli; branchial leaflets equal, each pair partially 
doubled on itself. ase small, cylindrical, with a byssal grove. Sexes 
united. Shell free or adhering, eared, ligament internal. Adductor 
muscles united. 
Genus, PECTEN—Linneus. 
Shell oblong or sub-orbicular, regular, equivalve, close; valves 
generally with scaly rays; ears unequal, the posterior with a sinus for 
the byssus ; hermaphrodite. 
P. zealandie, Grav, Dieff. N.Z, ii., p. 260; Voy. Erebus and 
Terror Moll., pl. 3, f' 73 P. adteffenbachit, Reeve, Conch. Ic., f. 88. Sub- 
orbicular, valves sub-equal, inflated, with about forty radiating sub-equal 
rough ribs, sometimes ornamented with scales ; ears very unequal, margin 
rather undulated ; variable in colour: yellow, red, purple, or brown. 
Height, 1°65 ; breadth, 1°6. 
Great Barrier Island to Stewart Island. Chatham Islands. 
P. gemmulatus, Reeve, Conch. Ic., f 111. Shell somewhat trian- ' 
gularly orbicular, thin compressed, equilateral, nearly equivalve, radiately 
densely ridged, ridges here and there larger; very beautifully, minutely, 
