PENTELASMIS* 



TESTA quinquevalvi, lateraliter compressa, 

 pedunculo affixa, valvis eontiguis, insequalibus, 

 basalibus majoribus, subtrigonis, convexiiiscu- 

 lis, antice ad basim acutis, dorsali elongata, 

 €arinata, apice acuto, superioribus elongato- 

 trapeziformibiis, infra acutis. Pedunciilus ple- 

 rumque longissimus, laevis. 



Shell with five valves, laterally compressed, attached by 

 a sometimes very long, smooth peduncle ; valves contigu- 

 ous, unequal, the basal largest, subtrigonal, a little con- 

 vex, acute at the anterior base ; the dorsal elongated, 

 lanceolate, keeled, sharp at its upper extremity ; upper 

 valves in shape like an elongated trapezium, placed be- 

 hind the lower lateral valves, acute at their lower extre- 

 mity. 



The Genus here given under the name of PenteJas- 

 mis^ is the typical genus of the family formed by Bru- 

 guiere's Genus Anatifera, and is the same as Leach has 

 called Pentelasmis, on account of its shell being composed of 

 five pieces. Even if we had supposed Briiguiere's name to 

 have had the right of priority, we could not have adopted 

 It, inasmuch as it is essentially bad, being founded on 

 the ancient absurd supposition of the Barnacle Duck being 

 produced from it: from whence also the commonly received 

 English name of Barnacle has been applied to these 

 shells. 



The species of this Genus do not appear to be nume- 

 rous, nor are they confined to any particular climate or 



* From itivrs quinque and zKxcriAX lamina (propria metalli.) We have 

 reason to believe that Pentelasrais has been adopted by Leach from Ray. 



