PLATE II. 



Fig. 1. Limopsis pelagica, Smith. 



Fig. 1. Seen from the left side, the mantle having been removed from that side. 



a, Buccal aperture ; b, anterior lip ; c, posterior lip ; d, foot ; e, visceral mass ; -7, gill ; h, branchial support ; 

 i, right lobe of the mantle ; k, anterior adductor muscle ; /, posterior adductor muscle ; m, anterior 

 retractor muscle of the foot ; m', posterior retractor muscle of the foot ; n, heart ; 0, intestine ; p, anus. 



Fig. 2. Limopsis minuta, Philippi. 



Fig. 2. Seen from the left side, the mantle having been removed from that side. 



a— e, As in the preceding figure ; /, internal plate of tlie gill ; y, external plate ; /i, branchial support ; 

 j, right lobe of the mantle ; j, point where the two lobes of the mantle unite posteriorly ; k, anterior 

 adductor muscle ; I, posterior adductor muscle ; m, posterior retractor muscle of the foot ; n, heart. 



Figs. 3, 4. " Cryptodon " moseleyi, Smith. 

 Fig. 3. From the left side, from which the mantle has been removed from the anterior adductor muscle to 

 the anal aperture, all along its adhesion to the giU. 

 6, Anterior lip ; c, left posterior palp ; il, foot ; g, gill ; i, right lobe of the mantle ; j, thickening of the 

 anterior margin of the mantle ; k, anal aperture ; I, anterior adductor ; m, posterior adductor ; n, 

 posterior retractor of the foot ; 0, heart ; p, intestine ; q, genital gland ; r, point where the two lobes 

 of the mantle are united posteriorly. 

 Fig. 4. Ventral aspect, the two lobes of the mantle having been thrown aside. 



a, Buccal aperture ; b, posterior lip ; c, anterior left labial palp ; e, byssal orifice ; /, visceral mass ; h, mem- 

 brane uniting the recurrent laniinoe of the gills ; n, cerebral ganglion. The other letters as in fig. 3. 



Fig. 5. " Cryptodon " luzonica, Smith. 



Fig. 5. Posterior aspect of the mantle margin. 



a, Free margin of the left lobe of the mantle ; b, posterior adductor muscle ; r, large branchio-pedal orifice ; 



d, anal aperture. 



Fig. 6. Semele profundorum, Smith. 



Fig. 6. Sketch of the animal, seen from the left side, from which the mantle has been removed. 



b, Anterior labial palp ; d, foot ; e, ventral plate of the gill ; e\ dorsal plate ; /, visceral mass ; /, anterior 



adductor ; m, posterior adductor ; n, posterior retractor of the foot ; 0, anal siphon ; p, branchial 

 siphon ; q, right retractor muscle of the siphons. 



Fig. 7. Lyonsiella jeffreysi, Smith. 



Fig. 7. The animal is seen from the left, after the removal of the mantle from that side. 



a, Buccal aperture ; b, fold surrounding the mouth ; d, foot ; d', byssus ; e, ventral plate of the gill 

 (external lamina) ; e', dorsal plate of the gill ; e", ventral plate of the gill (reflected or recurrent 

 lamina) ; /, visceral mass ; g, visceral ganglia ; h, pallial fold ; i, free margin of the mantle (pedal 

 orifice) ; /, point where the two lobes of the mantle are united behind the pedal orifice ; k, internal fold 

 of the branchial orifice ; I, anterior adductor ; m, posterior adductor ; p, anal aperture ; q, tentacles of 

 the branchial aperture ; r, point where tlie gill (dorsal plate) ceases to be fused to the mantle. 



Fig. 8. Lyonsiella papyracea, Smitli. 

 Fig. 8. The animal viewed from the left side, from which the mantle has been removed up to the line 

 along which it adheres to the gill. 



a, Buccal aperture ; b, anterior portion, and c, posterior portion of the fold surrounding the mouth ; d, foot : 



e, ventral plate of the gill ; e', dorsal plate of the gill ; /, visceral mass ; g, pallial gland ; h, mem- 

 brane uniting the gills to tlie mantle, and to the separation of the siphons ; i—m, as in the pre- 

 ceding figure ; n, posterior retractor of the foot ; 0, heart ; p, anal aperture ; q, tentacles of the 

 branchial aperture. 



Fig. 9. Lyonsia, sp. 



Fig. 9. The animal viewed from the left side, from which the mantle has been removed. 



b. Anterior palp ; c, posterior palp ; d, foot ; d', byssus ; e, ventral plate of the gill ; e', dorsal plate ; 



/. visceral mass ; g, membrane of the hinge ; A, membrane joining the gills to tlie separation of the 

 siphons ; j, point where the two lobes of the mantle unite behind the pedal orifice, which has here 

 become the byssal orifice, and exhibits an internal fold ; I, anterior adductor ; m, posterior adductor ; 

 n, anus ; 0, anal chamber ; p, anal aperture ; q, branchial aperture. 



Fig. 10. Lyonsiella ahyssicola. (Sars). 

 Fig. 10. The animal seen from the left side, from which the mantle has Ix'cn removed from the anterior 

 adductor to the branchial siphon. 

 a, Buccal aperture ; b, anterior labial palp ; c, posterior palp ; d, foot ; e, gill ; /, visceral mass ; g, visceral 

 ganglia ; h, membrane uniting the gills to the mantle and to the separation of the siphons ; »', free 

 m.irgin of the mantle (pedal orifice) ; j, point where the two lobes of the mantle unite behind the pedal 

 orifice ; I, anterior adductor ; m, posterior adductor ; «, posterior retractor of the foot ; 0, anal chamber ; 

 p, anal sfphon ; q, invaginate tentacles of the branchial aperture. 



