98 CARDIAD. 
siderations appear to support us in having transferred this 
species from the Kelliade to a separate family. 
It is well to mention that the figure referred to of this 
animal is incorrect, from the engraver having placed the foot 
and siphon at the wrong ends ; the position of each should be 
reversed. 
CARDIAD A. 
A family of only one genus, of nine species. This is a well- 
marked group by its radiating ribs, which are either nodose, 
spinous, or vaulted, with interstitial furrows of transverse 
waved striz. The tubes are short or sessile, but in some 
species an imperfect pallial stphonal smus may be seen. The 
animal is distinguished from every other bivalve tribe by the 
extraordinary length of the subcylindrical geniculated foot, 
and by the external surface of the siphons being clothed with 
Jong pendulous filaments. 
CARDIUM, Linneus. 
C. ecuinatum, Linnzeus. 
C. echinatum, Brit. Moll. 11. p. 7, pl. 33. f. 2. 
Animal suborbicular, pale yellow; mantle open, with the 
margin slightly dentated, pale brown, forming a branchial 
and anal siphon, which are ? of an inch long, in a shell of 
about an inch-and-a-half vertical and transverse measure ; 
they are of a dirty white hue, united or soldered on each 
other, and have not the aspect of a single sheath; the anal is 
rather the shortest and smallest, and protrudes a plain globular 
valve at its termination; each is frmged with about 15-20 
white cirrhi, having at thew bases short, dark yellow, and 
minute close-set brown lines, which give the orifices of the 
siphons the appearance of being encircled by a fine line, and 
on the external surface of each there are long, somewhat 
curved white filaments, which also for a short distance clothe 
the mantle above and below them. The foot is subcylindrical, 
