FISSURELLA. 157 



F. SPONGIOSA Carpenter. Unfigured. 



Shell elongated, compressed, conical, narrower in front, dilated 

 behind ; outer surface not lirate or striate, but having a sort of 

 spongy texture ; green, the young with lines, adult with radiating 

 spot of chestnut. Aperture elongated, obscurely trilobed ; inside 

 shining, ashen-white, showing more or less the spots of the outside ; 

 marginal callus of the hole purple-red ; muscle-cicatrix irregular, 

 calloused inside and punctulate anteriorly ; margin acute, hardly 

 crenulated, in young shells spotted with chestnut. ( CprJ) 



Length ?, breadth in front '3, behind '43, alt. '24 ; hole '14 by 

 04 inch. 



Mazatlan ; extremely rare. 



F. spongiosa CPR. Mazat. Cat. p. 219, 1857. 



Carpenter says : " Only two specimens were found of this singu- 

 lar little shell ; the younger one of which', though most highly col- 

 ored, is diseased within, and displays neither the livid color of the 

 fsecal callus nor the punctures on the anterior part of the general 

 callosity which fills up the space between the irregularly jagged 

 muscular scar and the region of the hole. It most resembles F. cat- 

 illus Reeve. The external surface is loose and rough." 



Unfigured species. 

 F. RADIOSA Lesson. 



The shell of this Fissurella is oval-oblong, lightly convex, the 

 sides a little depressed. The fissure is elongated, contracted, 

 provided with two teeth on each side, and a little in front of the 

 middle of the shell ; its circumference is smooth, white. The upper 

 surface is covered with straight ribs radiating from center to circum- 

 ference, enlarging toward the latter. These ribs are traversed 

 by concentric fine, close striae, which make the surface granular. 

 The ribs are separated by profound narrow grooves, and they are 

 arranged with three smaller ribs between each pair of larger ones, 

 all over. The outside is golden yellow, with gradually widening 

 violet-purple rays. The edge is regular, denticulated below, white 

 and purplish-black alternately. Inside smooth, porcellaneous white. 

 (Less.) Length 13, breadth 7, alt. 2 lines. 



Falkland Is. 



F. radiosa LESS. Voy. de la Coquille, ii, pt. 1, p. 411. 

 Compare F. darwinii. This species has not been figured, or noticed 

 in the monographs. 



