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UNITED STATES NATIONAL MUSEUM BULLETIN 296 



Figure 28. — Cryptophialus lanceolatus, new species, from Tridacna maxima from Heron 

 Island, Australia: a, female side view; b, detail of opercular plates opened from the comb 

 collar (carinal) end; c, d, detail of operculum, attachment (rostral) on left end, medial 

 barbs (about 12 each) not included; e-h, opercular horizons of different specimens, with 

 length in millimeters, attachment (rostral) on right: e, 1.25;/, 1.40; g, 1.25; A, 1.15; i, 

 mouth field and long labrum; j, mandible; k, first maxilla; /, detail of portion of terminal 

 cirrus; m, prominent tooth on mantle exterior; n, sketch of mature male, side view, 

 showing curious "beak" on bottom, and recurved antennule on top; o, male, ventral 

 view; p, sketch of cyprid larva and a detail of the "peg plates." 



The mantle is not strongly muscular. The shape of the mantle is 

 that of a bottle with a long, bent neck. The aperture is at the top end 

 of the neck, and the attachment area is at the top of the widest 

 flange on the dorsal side. The mantle aperture area is a brownish 



