ACANTI II 9 



p, 28 L829 : tvpe Oh. /oMtMtfaru Sow. < - 



C\'\i. in DM i Nai. Mu. Issl, pj 



(1882- type - to CPB, 



Valves partly covered, // nnle.r'nn- A//-/-/'//// rml intin'i rib 

 l>oxteritn- i'ii/i-t' hnrinij ///'' in.^'r{iini-]ifiifr ////// / .</'// 7 ' 



/W///W <'<f</>, ,,n<f <l iriilt; fmith/r. flftUI /// ///>' //,/',/,/ 



(iirdle with lar^e, dt-nx- tufts of glistening spicules. Type, C.fatci- 

 cHl'tri.-i L. 



In this, the typical section, the tuil valve has been further differ- 

 entiated from the primitive type than in the oth-r .- 

 bain of the girdle, and especially the tufts, are more exuberantly 

 developed than in any other group of Chiton*. The va! 

 greatly in the degree to which they are buried in the girdle. The 

 species are numerous, but owing to the similarity of the .-mlpture 

 they are very hard to distinguish, even when well described. 



(1) Species of European and African S> 



A. FASCICULARIS Liinie. PI. 4, figs. 77, 78, 79. 



Shell elongated, moderately convex, more or less distinetlv car- 

 mated. Surface dull, varying much in color, "brown, chocolate, 

 orange, yellow, pinkish or red, now and then mottled or streaked 

 with white, pale green or brown." 



Median valves broadly subtriangular (seen detached), the I 

 slightly projecting, latero-anterior outline of tegmentum coi, 

 Latero-pleural areas covered with flat or concave granules, which are 

 ovate-oblong or drop-shaped and rather remote. Dorsal areas tri- 

 angular, not abruptly defined at the edges, rather flattened and 

 longitudinally obsoletely striated. Anterior valve granulated, 

 lower edge of the tegmeiitum slightly and obsoletely angular. 

 terior valve with subcentral elevated mucro. 



Interior greenish, often roseate along the cavity. Insertion-; 

 of posterior valve having between the two slits a small 

 \\ave or sinus with a slight lobe on each side. 



Girdle moderately broad, more or less closely covered with >hrt 

 spicules which are usually tawny or grayish; and a thick tn 

 greenish or whitish bristles at each Mitiiiv, fmirsurh tuftsanuin.. 

 head valve. Periphery of girdle fringed with spines longer than 

 those covering the rest of the girdle, but >horter than tho.-e o( 



tufts. 



