PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 413 

 A. Without a cordon. 

 A. Muzzle with lappets. 

 a. Blind. 



Pecfmodonta Dall. ^ f ? = ^ ^. 



(14) V (3-3) oy 



6. With eyes. 



ScutelUna Gray. Typical species not yet examined. 

 



Acmcea Esch. 



ColliseUa 



(3-3) 0* 



B. Without muzzle lappets. 



ColliseUa Dall^ s. s. ^-jn ^ — o-^ 



ColUsellina Dall. .— ^ . 



2 (2-1-1-2) 2 



B. With an interrupted cordon j no lappets. 



Lottia {Gray) Cw i (2-14-2) l ' 



C. With complete cordon ; no lappets. 



Scurria Gray (notCpr.). . 



•^ ^ ^ ^ 1 (2-1-1-2) 1 



Family PATELLID^. 



Without a cervical branchia, but with a more or less complete cordon; 

 muzzle papillose, not frilled, marginated, or with lappets. 



A. Branchial cordon couiplete. 



a. With rhachidian tooth; branchial lamelliB arborescent, produced; 

 sides of foot smooth. Ancistromesus. 



Ancistromesus Dall. 



3 (1-2-2-1) 3 



b. Without rhachidian tooth; branchial lamellae short, linguiform. 



Fatella. 



Patella Linn6. Foot smooth, branchial lamellse subequal all around. 

 

 3 (1-2-2-1) 3' 



