230 AMPHIDUOMUS, GROUP XVIII. 



latter shells connect the supposed species in every direction. Selected 

 specimens may be classified according to Mr. Fulton's arrangement, 

 but the intermediate forms repudiate it as unnatural. My plates 

 were arranged before the forms were completely studied, and so do 

 not show the connections as well as might be desired ; but as an in- 

 stance of the color-form chains occurring, I would mention one con- 

 necting quadrasi and versicolor through pi. 71, fig. 78, f. 75, pi. 66, 

 f. 47, f. 43, pi. 71, f. 91 ; or from pi. 66, f. 47, we may pass to pi. 

 71, f. 89. And the immature shells of this last form are exactly 

 like some dubius, in stripe and band marking. The latter form 

 (dubius) also connects directly with the maculate form of quadrasi 

 (pi. 71, f. 74, 75) through several specimens before me. 



Color-form solidus Fulton. PI. 71, fig. 76. " Smaller and more 

 solid than typical quadrasi, subangulate at the periphery ; last whorl 

 either white, reddish-brown or yellow, with a broad white spiral 

 band just below the suture; upper whorls either plain white or with 

 narrow, oblique, interrupted, light brown stripes" (Fulton}. 



Palawan. 



Fig. 76 is Fulton's type. 



Specimens before me (pi. 71, figs. 72, 73, 74, 75 ; pi. 66, figs. 47, 

 48), have the last whorl yellow except for a broad white belt below the 

 suture, \vith close blue-green lines or scarcely any, the suture with a 

 yellow or red margin or none; the spire whitish with purplish flames 

 forked above, or cut by a median whitish line into two series of 

 purplish spots, the upper series split or forked, apex with a small 

 dark dot; the columella with a small reddish area or none. Some- 

 times the purplish rnaculation of the early whorls extends upon the 

 last ; and in most of the shells the parietal wall shows a basal spiral 

 band visible on looking into the aperture, but not reaching the last 

 whorl. The specimens figured are from Balabac. This series forms 

 a practically complete transition to versicolor and dubius. 



Color-form versicolor Fulton. PI. 71, figs. 8491. Variable in 

 form from oblong- to ovate-conic, imperforate. Apex usually with 

 a blackish dot, the spire either plain whitish or fleshy or striped with 

 brown flames forked or dissected above; the last whorl either (fig. 

 87) cream-buff, the tint deeper below, or (fig. 86) yellow, suffused 

 toward base and suture with carmine, and with some greenish spiral 

 lines, the lip pink, columella red-purple, or (figs. 90, 91) buff with 

 wedge-shaped dark green bands behind tlie lip, or (figs. 88, 89) 



