2 PROCEEDIKTGS OF THE ISTATIOFAL MUSEUM vol. 72 



periostracum or to section the shell to determine the fact. On the 

 outside the rays are single, narrow " clear-cut " and reddish, but 

 on the inner margin many of them are double, broad, blurred, purple, 

 or deep lavender. A section across the rays near the ventral margin 

 shows that there they go entirely through the calcareous portion of 

 the shell. In sections made nearer the beaks they go at least part 

 way through. 



Several of the specimens received from Professor Teisseire con- 

 tained young. When collected, these specimens were not cleaned, and 

 the young of various ages are included in the dried flesh of the 

 females. The young are in perfect condition. 



A fine specimen of G . felipponei (Cat. No. 365390) from the Bay 

 of Colonia contained embryonic and nepionic shells. The latter 

 were probably not yet developed to the age of extrusion, as they are 

 smaller than one would expect from the size of the adult. In these 

 young, which are very pale straw color, there is a splash of purple 

 on the anterior area and one on the posterior. Immediately after 

 the close of the embryonic stage fine radiating lines of lavender make 

 their appearance. Such lines occur in specimens not more than a 

 millimeter in length. 



CORBICULA (CYANOCYCLAS) TBISSEIKEI, new species 



Plate 1, figs. 1, 2 



Shell rather thin, nearly elliptic, rounded and slightly narrower 

 in front, more broadly rounded at the rear; a little inflated, beaks 

 rather low, situated at the middle of the dorsal line, which is well 

 arched. Ventral line regularly curved. Posterior and anterior 

 ridges not well defined, the descent to the margin more abrupt at 

 the rear than in front. Periostracum generally clothlike and dull, 

 but slightly glossy on the convexity of the shell. Sculpture of 

 numerous concentric striae, which develop into fine ribs on the an- 

 terior area. Color brownish with an olivaceous cast and with three 

 obscure broad fuscous rays in the vicinity of the posterior ridge, 

 and with faint radiating lines of color over the general surface. 

 The shell being "dead" the color of the interior has changed to 

 nearly uniform purple. (Fresh specimens have the interior gay with 

 pink, lavender, and purple, with three broad purple interrupted 

 rays indicating the location of the three fuscous rays of the ex- 

 terior — a number of fine lavender rays unequally distributed.) In 

 the right valve the middle and posterior cardinal teeth are distinctly 

 grooved on the summit, the anterior cardinal small and thin. In 

 the left valve none of the cardinals is grooved, and the posterior 

 one is small and thin. In both valves the cardinals are widely 

 divergent. In the right valve the two posterior laterals are rather 



