CLASS BRACHIOPODA 
225 
edged medial septum extending six-fifteenths of the distance from the 
cardinal apex toward the base; teeth long, diverging at an angle of about 
120°, obliquely transversely striated, the sockets behind them deep, in¬ 
ternally transversely grooved; lamella supporting the teeth deep-seated, 
extending obliquely from the sides of the valve; crura starting from the 
cardinal margin at the inner ends of the teeth, extending in a straight 
line obliquely downward and forward, united to the teeth for about half the 
whole length by an excavated lamina; the free ends of the crura slightly 
wedge-shaped, parallel-sided, and abruptly truncate at the ends. From the 
upper part of the inner edges of the crura on each side an excavated lamina 
is given off, which reaches the median line above the septum, to which, 
and to each other, the laminae are solidly attached, forming a narrow 
spondylium. The front edge of the spondylium is indented mesially and 
there is an impressed mesial line, extending upward, on each side of which, 
in old specimens, the laminae are made prominent by a callous deposit. 
Behind the spondylium the attached surface of the septum is widened, so 
as to support part of each lamina as well as their line of junction. On 
either side of the septum, between it and the supporting dental lamina, a 
pointed recess extends below the spondylium toward the cardial margin. 
The surface of this valve, like that of the other, is too polished to retain 
much of the muscular impressions. The muscles, however, are inserted 
on each side of the septum and above its lower end, much as in H. psittacea. 
An average specimen measures 17 mm. high, 16 mm. wide, and about 
10 mm. in antro-posterior diameter. (Dali.) 
Type in U. S. N. M., No. 123148. Type locality, Cortez Bank, Cali¬ 
fornia coast, in 984 fathoms, U. S. Fisheries Commission Station, 2919. 
Range. Kamchatka, Alaska, British Columbia, off Washington coast, 
and Oregon to San Diego, California. Also Japan. 
Family TEREBRATELLID2E. 
Genus PLATIDIA Costa, 1852. 
Shell minute, conspicuously punctate; foramen large, encroaching 
equally on both valves; hinge area small, straight; loop not reflected, 
attached to a small forked process in the centre of the valve. 
Type. Apparently Or this anomioides Philippi. 
Distribution. Mediterranean, West Indies, Isle of Bourbon, Cali¬ 
fornia, and Lower California. 
Range in time. Chalk of Europe; Pleistocene, Signal Hill, Los 
Angeles County, California. 
