CHARACTERISTIC DEEP-SEA TYPES. — BRACHIOPODS. 77 
small species extends to a depth of nearly 500 fathoms. A 
most common Atlantic species, 7. caput-serpentis (Fig. 318), is 
found along the eastern coast of the United States as far south 
Fig. 317. — Terebratulina Fig. 318. — Terebratula eaput- 
Cailleti, 4. (Davidson.) serpentis. 1:25, (Davidson.) 
as Cape Cod. A species of Platydia, identical with the Medi- 
terranean P. anomioides (Figs. 319, 320), has been dredged by 
the * Blake" in 237 fathoms. It represents the group of brach- 
iopods with shells having loops and conspicuous perforations. 
PGi i? 
Fig. 320. 
Platydia anomioides. $.  (Davidson.) 
A few specimens of Crania (Fig. 321), a genus not before 
obtained on the American coast, were dredged by Pourtalés off 
the Samboes and Sand Key, at 
depths ranging between 100 and 
200 fathoms. Living specimens of 
Discina atlantica (Fig. 322) have 
been taken by the “ Blake” and by : 
the Fish Commission at the depth Fig. 321. 
of over 2,000 fathoms. They are Crania Corti" Fig. 922; — Discina 
a lesii. 23%. (Dall.) atlantica. 2. (Ver- 
usually attached to concretions. vill.) 
The simple and compound Ascrprans are eminently littoral 
and shallow-water types, and but few of them extend to any 
great depth. Neither the “Blake” nor the “ Challenger” col- 
lected any very remarkable abyssal types, and the species were 
either closely allied to or identical with well-known genera. 
