318 Bvlletin Vanderhilt Marine Museum, Vol. VII 



of the shell and usually shows broken lighter markings, corres- 

 ponding to the distal end of the light radial bands of spots. The 

 inner margin of the lip has a marginal band of brassy yellow, 

 bronze or dark metallic green iridescence, while the pearly nacre 

 is highly iridescent, frequently having a steely lustre. 



The shell is more convex than P. maxima and does not usually 

 attain so great a size. P. margaritifera has a shorter hinge, the 

 typical hinge margin being equal to about five-eighths of the 

 pearly surface of the valve, measured from the anterior to the 

 posterior margin. The anterior angle of the hinge is more dis- 

 tinctly separated from the shell than is the case in maxima and the 

 posterior end of the hinge usually forms an obtuse angle where it 

 meets the posterior margin. The posterior margin has no sinus. 

 Ventral to the byssal notch the anterior margin projects much 

 further forward than it does in P. maxima. 



The lappet-like processes of the lip in the younger specimens 

 are more closely crowded, more numerous, relatively longer and 

 narrower than those of maxima, having the appearance of deep, 

 U-shape scales. 



As pointed out by Dr. Baini Prashad (Siboga, 1932, p. 99) , the 

 "Siboga" representatives of this species "vary a great deal in the 

 shells, being orbicular, or as in the case of some shells from Sta- 

 tion 144, very much elongated in the dorso- ventral direction and 

 the outline becoming somewhat elongated-ovoid. The surface 

 markings and the colouring are also very variable." 



It is regrettable that the Smithsonian Institute has sponsored 

 another synonym that must be added to the long and excellent 

 synonymy of this species, Pinctada margaritifera (Linne), as 

 given by Mr. Prashad, namely, the recently described Pinctada 

 galtsoffi Bartsch, from the Pearl and Hermes Reefs, Hawaii. 



Analysis of the very casual description of Pinctada galtsoffi 

 Bartsch shows the type to be a larger than average size specimen 

 of pearl oyster, but one possessing : (a) A hinge typical of P. mar- 

 garitifera; (b) the general contour of the valve is one of the well 

 known variations of the more usual orbicular shaped shell ; (c) 

 the colour, which the author describes, falls entirely within the 

 range of variation long known for this species, except the nota- 

 tion : "The outer margin in the type is yellowish horn-coloured." 

 The marginal borders of young paratypes, as described by Mr. 

 Bartsch, is typical of P. margaritifera. The Galtsoff material was 



