114 LITTORINID.E. 



rather broad wavy and somewhat remote tawuy or rnfous 

 longitudinal streak-like spots, that run from the upper 

 suture, and do not either reach the lower one or inter- 

 mingle usually with the second series which is disposed 

 upon the base of the final volution. The more solid 

 examples are usually marked on the three last whorls, 

 with very numerous narrow, and often oblique longitudinal 

 folds ; these occasionally, especially on the more fragile 

 individuals, become obsolete, and sometimes the surface 

 appears almost smooth, yet when closely scrutinized the 

 traces of folds are almost always perceptible ; usually, 

 also, the costal interstices are spirally traversed by rather 

 distant stria;, but these likewise are often very obscure, 

 and are chiefly distinguishable (where the ribs vanish) 

 upon the base of the body-whorl. There are six or seven 

 whorls, which, though only divided by a nearly horizontal 

 simple yet well pronounced suture, are peculiarly well 

 defined, owing to their being decidedly convex, or even 

 ventricose ; they are a little more shelving above, are 

 gradual as to their longitudinal increase, and end in a 

 very small but blunt apex. The body, which is much 

 rounded, rarely exceeds two-fifths of the entire length 

 of the shell ; it is more or less abruptly rounded at its 

 basal declination. The length of the penult is not, in 

 general, one half its breadth. The mouth is small, and in 

 the more stunted forms occupies two-fifths of the ventral 

 length ; but in the more produced varieties is only half 

 as long as the spire above it : it is typically suborbicular, 

 and projects towards the base, which latter is broadly 

 rounded. The throat is quite smooth. The outer lip 

 is much arcuated, and more frequently acute, but is some- 

 times marglnated externally by a narrow but prominent 

 varix-like rib, which is not distinguished from the general 



