CHARACTERISTIC DEEP-SEA TYPES. — LAMELLIBRANCHS. 73 
and largest of its genus, white, with a golden epidermis, is pecu- 
liar in its shape, which resembles that of a small member of the 
Veneridz. A delicately sculptured Cardium, sometimes painted 
with bright touches of yellow and scarlet, Cardium perama- 
bilis (Fig. 304), the most lovely species of the genus from deep 
water, shares with the little Pecten ( Amusium) Pourtalesianum 
Dall the distinetion of bright tints where pallor is the rule. 
The shell is white, but the spines covering it are orange or 
crimson. A common and characteristic deep-water form is 
Limopsis aurita Brocchi, well known as a tertiary fossil in 
Europe. A small brown Astarte is almost ubi- 
quitous, ranging in depth from 15 to over 1,600 
fathoms, and in locality from the tropies to New 
England. The northern specimens attain many 
times the size of those from the Antilles. A 
highly polished rich golden brown Modiola, 
M. polita V. & S. (Fig. 305), allied to.our com- 
mon mussel, attains a large size in great depths 
on both sides of the Atlantic. But its shell is 
very thin ; it spins a large nest of byssal threads, gli 
resembling a handful of cotton waste thoroughly pulita: d. 
drenched with the finest mud, so worthless in 
appearance that only a biologist would suspect the treasure 
hidden within. 
The Cetoconcha above mentioned are characterized by gills 
reduced to a mere interrupted 
line of low lamelle on the ven- 
tral surface; they are related 
to Poromya, which has ordinary 
gills. But there is another 
group, abundant in deep 
water, called Cuspidaria, still 
more remarkable in having ap: 
parently no gills at all; their 
shells are provided with a long slender rostrum, like a handle, 
as shown in C. microrhina Dall (Figs. 306, 307), dredged from 
continental depths. A striking group, from the beauty of 
form and sculpture exhibited by its species, is Verticordia, the 
Fig. 306. —Cuspidaria mierorhina. +. 
