CHAMA.—Prats I. 
Variety 8. (Fig. 1 6.) 
Testa lamellis brevioribus, minus frondosis, numerosioribus, 
wregularibus sed magis equalibus ; omnino purpurea. 
Shell with the lamelle shorter, less frondose, more nume- 
rous, regular but more equally distributed ; purple. 
Broperip, Trans. Zool.Soc., vol.i. p.302. pl.38. f.1 and 2. 
Hab. Var. a, Island of La Plata, West Columbia (dredged 
up from a rock of coral to which it was adhering at a 
depth of seventeen fathoms) ; var. 8, Gulf of Tehuan- 
tepec, Mexico (dredged up from sandy mud attached 
to large Avicule) ; Cuming. 
It is impossible to do justice in a figure to this magni- 
ficent species; the bold and elegant structure of the 
frondose laminze, towering one over the other, coupled 
with their vivid colouring, render it eminently beautiful. 
Each lamella in the middle and posterior rows of Var. a, 
is formed like a broad expanded fan-shaped leaf, radiately 
plaited on the upper surface, and of a rich saffron colour, 
slightly tinged with purple; whilst the hollow surface 
beneath is smooth and peculiarly tinted, the ground colour 
being of a purer and brighter yellow, shaded at the base 
with a rich crimson purple, rising, as it were, out of the 
root. The Var. 8 is of an uniform purple-lake colour, 
still exhibiting sufficient indications of yellow in places 
to show its affinity in this respect; the lamellz, though 
broken and irregular, are nevertheless characterized by the 
plaited structure on the outer side. 
It is unnecessary to refer to the sculpture of the under 
valve in this genus, unless it presents, as in the Spondyli, 
a difference of structure ; that is by no means unfrequently 
the case, but in the species under consideration the cha- 
racter of the attached valve is the same, allowing for irre- 
gularities occasioned by circumstances of habitation. 
Species 2. (Mus. Cuming.) 
Cuama Broperipit. Cham. test oblongo-ovatd, subtri- 
gond, valvd superiore squamis fornicatis oblongis suban- 
gustis, valde wrregqularibus, inferiore lamellis imbricatis, 
subplicatis creberrimé ornatd, valvis ambabus umbones 
versus radiatim striatis, intus valvarum marginibus 
minutissime crenulatis ; valvd superiore purpureo-rubra 
squamis albidis, inferiore squamis aurantio-rubris, intus 
albidd, margines versus purpured.. 
Broperrp’s CuamMa. Shell oblong-ovate, somewhat tri- 
angular, upper valve very closely ornamented with 
very irregular narrow oblong vaulted spines, the lower 
with slightly plicated imbricated lamelle, both valves 
radiately striated towards the umbones; margins of 
the valves within very minutely crenulated; upper 
valve purple-red, scales whitish, lower with the scales 
uniform orange-red, interior white, margins purple. 
Chama Pacifica var., Broderip. 
Fiah. Lord Hood’s Island, Pacific Ocean (found attached 
to large Avicule at the depth of six fathoms); Cuming. 
I dedicate this species to the author of the admirable, 
though limited, paper on Chama in the Trans. Zool. Soc., 
who, I think, has erred in including this under the head 
of C. Pacifica; there appears to be an uniformity of cha- 
racter in this variety distinct from that species, which is 
of a more oblong crescent shape, with the spines fewer 
and more erect, and of a peculiar livid purple colour. 
Species 3. (Pl. 1. Fig. 3, and Pl. VI. Fig. 3 2.) 
CHamMa ImBricata. Cham. testé hemisphericé ovatd, 
circuiter trigond, valod superiore lamellis foliaceis im- 
bricatis, confertissimis, plano-declivibus,marginem versus 
ornatd, umbonem versus muticé aut subtiliter oblique 
liraté, postice squamarum minutarum seriebus trans- 
versis exculpté; valvd inferiore liris rudis undatis, 
oblique dispositis, ad extremitatem superiorem squa- 
matis, ornatd ; valvarum marginibus internis obsolete 
minutissime crenulatis ; alba, squamis lamellisque un- 
dique albis, interstitis inter series squamarum lirasque 
sanguineo-purpureis, intus alba, marginibus purpured. 
THE IMBRICATED CHaMA. Shell hemispherically ovate, 
circuitously triangular, upper valve ornamented to- 
wards the margin with imbricated foliaceous lamellee, 
very close-set and slanting forward one over the other, 
towards the wnbone smooth or finely obliquely ridged, 
posteriorly engraved with transverse rows of minute 
scales ; lower valve ornamented with rude undulating 
ridges, arranged obliquely and scaled at the upper 
extremity, internal ridges of the valves obsoletely 
very minutely crenulated; white, scales and lamellz 
ivory white throughout, interstices between the ridges 
and rows of scales deep blood-red purple, interior 
white, faintly stained with purple at the margins. 
Bropertp, Trans. Zool. Soc. vol. 1. p. 304. pl. 39. f. 2. 
Hab. Lord Hood’s Islands, Pacific Ocean (found attached 
to large Avicule at depths ranging from three to 
seven fathoms) ; Cuming. 
Mr. Broderip includes a far wider range of varieties 
under this head than I can admit; the shell figured by 
him at Pl. 32. f. 3.-of the Trans. Zool. Soc. is in my 
opinion considerably removed from it. I incline rather to 
think, on the contrary, after the most patient investigation, 
that the present species is one in which the characters 
above described are more than usually permanent. 
For the sake of avoiding the imputation of having a 
desire to multiply species unnecessarily, I have represented 
at. Plate VI. Fig, 3 4. a specimen of Chama imbricata in a 
very immature state, from quite another locality (Mauri- 
tius) found under very different circumstances (attached to 
arough piece of madrepore), and yet possesing all the 
characteristics detailed above, both in regard to colour and 
arrangement of sculpture ; namely, the rude oblique ridges 
of the lower valve, and the snowy white imbricated lamelle, 
‘with the transverse rows of minute white scales, deep 
purple in the interstices, on the posterior side of the upper. 
