106 IN. .rim 



Lateral areas slightly raised, sculptured Longitudinally with ///- 

 row zi'/:<i<i i/i-woe*, the eleva\'>n* liu-,' t n tin m (Int. //</ der 



to be io.</ munife/if pHxfii/nt'. the ptiMules whitish. 

 nil areas coven d with <m CXCCSSlVely ////'. ('/<><>' (jiiium 



/licit be<'tnnr. *tiyht/y <*//>/ / tu;i,-<l ' where the 



_li-it<lmtl/y brnmif nt> <<// info Ion f/ifniliim/ i-inr." 'jicitKi (i 

 /////' <ij,i to the pi' in- 1, especially to the part Iving at and 



iiiuii.Mliat.lv in front of the diagonal line. Knd valves having con- 

 centric /iir/aL and a minute granulation, like the lateral 



areas; |>o>terior valve having a moderately elevated, central unilio, 



rior >loj.c concave. Interior liirht rray-l)lue or white : ani> 

 valve with !>, central valve 1, po>teri,r valve ! slits. Teeth .-mooth, 

 >harp. Maves narrow, solid; sutural plates wliiti.-h, rather wide 

 and low: sinus Hat, angular. 



Girdle whitish clouded with blue, or blue marbled with white, 

 generally having some small yellow or orange flecks. It is densely 

 covered with imbricating, deeply striated scales. (PI. 20, fig. 24.) 

 Length 14 to 15, breadth 8 mill. 



St. Thom<t- 



GRAY, Specil. Zool. p. (1828). KI:I:\ i , 

 Conch. Icon. t. 22, f. 144. 



The coloring of this species is extremely variable, and the sculpt- 

 ure, while it is unmistakable when seen under a sufficiently hi^h 

 I lower, still varies considerably. The side areas and end valves 

 are generally sculptured with the concentric zigzag grooves 

 described above (fig. 23) ; but occasionally these become &o irregular 

 and broken that the surface appears coarsely granulous or scaly. 

 The West COUM species di*par 8owb. and utl<nn*ii Cpr.. afl 

 well as the /V,>-M*X of Sowerby, all belong to the #fi'i<t/(itnx ^rouj), 

 and are closely allied in sculpture. There are also a number of 

 described West Indian Ischiiochitons which seem to be either mere 

 >ynonyms of /. >//W<//"*, or closely allied forms, the xact status 

 of which it is (piite impossible to fix with certainty until the origi- 

 nal types can be examined by a competent person, thoroughly 

 ar|ii:iinted with the Mibject. The original descriptions of these 

 forms here follow. 



C. Bquamuloetu C, 1- Adams, shell olivaceous, ornamented with 

 a pale green dorsal line; lateral areas covered with prostrate 



