40 LITTORINID.E. 



Littorhia tenebrosa, Forbes, Make. Moneiis. p. 18. — Macgti.l. Moll. Aberd. 

 p. 138. — Brit. Marine Concli. p. xxxix, f. 92 (changed 

 from Turbo t. p, 166). — Brown, 111. Conch. G. B. p. 16, 

 pi. 10, f. 18, 1.9. — Gould, Invert. Massachus. p. 2.59, 

 f. 175*.— Dekay, New York Moll. p. 105, pi. 6, f. lOG. 



Of this shell there are two varieties, the one ridged, the 

 other smooth, that pass imperceptibly into each other ; of 

 these we regard the latter, which is by far the commoner, 

 as the normal form. 



The shape ranges from ovate-conic to oblong-conic, the 

 larger examples being ordinarily the less produced ones. 

 The colouring is very variable, being yellow, purplish- 

 chocolate, livid brown, scarlet, or chocolate brown ; in the 

 latter case, with an occasional zone of orange in the middle 

 of the body-whorl. Sometimes, too, the surface is equally 

 and rather broadly zoned with orange red and dusky brown. 

 A not unfrequent and very characteristic style of painting, 

 is where a ground, that ranges from fulvous brown to 

 almost black, is mottled by irregular but somewhat spi- 

 rally disposed, short angulated streaks of white, yellow 

 or orange. The texture is often thin, rarely, if ever, 

 solid, and at most is moderately strong ; the surface has 

 but little lustre, and ranges in sculpture, from almost 

 smooth, or merely impressed with very fine and undulated 

 spiral lines, to spirally ridged. There are six much 

 rounded and often very bluntly subscalariform volutions 

 that terminate in a rather fine apex, and rather slowly 

 increase in length, though they quickly enlarge in breadth ; 

 of these the lower ones are peculiarly well defined, the 

 rise from the suture being almost perpendicular. The 

 spire, viewed from above, occupies from three-sevenths to 

 one-half of the entire length ; the penult whorl is about 

 half as long as it is wide. The body whorl is always 

 short (compared with our native species), and is some- 



