VII 



MOLLUSGA— SYSTEMATIC REVIEW 



19 



Lutrariidse, Myidse {Miia, Corhula). Fam. Glycjrmeridae {Ghjcymeris, Saxicava 

 [boring mussels]). Solenidse: shell with anterior and posterior cleft; foot very- 

 large {Solemcurtus, Cxdtcllus, Ensis, Soh'n). 



Sub-Order 6. Pholadacea. 

 Dimyarian with closed mantle and well-developed siphons. Foot varies, and is 



M, 3rn Ea. m 

 J I f 





Fio. 27.— Anatomy of Pholadidea, left aspect (after Egger). Lettering as before. In addition, 

 Npa, Npp, anterior and posterior nerves of the mantle edge ; mo, anterior aperture of mantle ; Ks, 

 sac of the crystalline stylet ; Kv, branchial vein ; o!, anterior upper mantle lobe ; Rpp, posterior 

 retractor of the foot ; Ss, partition between the two siphons ; JVf^, accessory adductor; mb, intestinal 

 csecum ; x, pericardial section of the kidney, which opens into the pericardium by means of the 

 renal funnel at v. 



Fio. 28.— Anatomy of Jouannetia Cumingii, left aspect (after Egger). Lettering as in 



last figure. 



sometimes rudimentary. Shell open, often having accessory pieces added to it. 

 Fam. Pholadidse: boring mussels {Pholas, Pholadidea [Fig. 27], JouMnnetia [Fig. 281, 



