294 Bvlletin VanderbUt Marine Museum, Vol. VII 



The sutural plates have a widely, deep, rounded contour an- 

 teriorly, and one each about three-fifths as deep as the related 

 adjacent posterior area of the valve. The sutural plates of a valve 

 have a median sinus between them about one-half as wide as one 

 plate. In the second valve this is smooth, but in the remaining 

 valves it is finely denticulate. There is one slit present in each 

 intermediate valve ; the teeth are sharply, deeply pectinated out- 

 side. The eaves are narrowed, projecting slightly downward just 

 above and very narrowly grooved outside of the teeth. 



Posterior valve: This has a very prominent mucro near the 

 posterior end, the median area anterior to it being horizontal, the 

 slope behind it being vertical. The jugum anterior to the mucro 

 is similar to that of the preceding valve. The pleural areas are 

 marked with radiating lines of squamae alternating with grooves, 

 nearly devoid of eyes. The vertical region posterior to the mucro 

 drops vertically from the diagonal line, is convex, covered, except 

 near the mucro, with radiating lines of imbricate squamae, alter- 

 nating with linear grooves in which the eyes are very numerous, 

 in concentric series, especially abundant just behind the mucro, 

 but also occurring regularly spaced (as on the anterior valve) in 

 the grooves between the ridges down to the outer margin of the 

 valve. There are fifteen slits present, these being rather shal- 

 low; the posterior teeth somewhat directed forward and deeply 

 pectinated. 



References : Chiton confossu£, Gould, A. A., Proc. Boston Soc. 



Nat. Hist., July, 1846, p. 143 ; in Wilkes, U. S. Explor. Exped. 



Mollusca, 1852, vol. XII, pp. 143, 327; atlas, vol. XII, pi. 35, 



figs. 434-a, b ; Otia conchologica, p. 5. 

 Chiton (Lucia) confossus, Gould, A. A., Otia Conch., 1846, p. 242. 

 Lucia confossa, GouLD, A. A., Proc. Boston Soc. Nat. Hist., 1862, 



vol. VIII, p. 283.— Dall, W. H., Proc. U. S. Nat. Mus., 1878, 



vol. I, p. 298. 



Tonicia confossa, Tryon, G. W., and Pilsbry, H. A., Man. Conch., 

 1892, vol. XIV, Polyplacophera, p. 210, pi. 57, figs. 33-36.— 

 Melvill, J. C, and Standen, R., Journ. Linn. Soc. London, 

 Zool., 1899, vol. XXVII, No. 174, p. 180.— NiERSTRASZ, H. F., 

 Siboga-Expeditie, monogr. XLVIII, 1905, p. 90, pi. 2, fig. 31, 

 pi. 6, 165. 



