1464 MVCF.ToronA 



Dorsal margin straight : antero-dorsal angle sharp ; postero- 

 dorsal angle rounded. The ventral margin is convex, sloping 

 to the last third of the shell, whence it gradually ascends. The 

 anterior end is regularly rounded, with a low, rounded extrem- 

 ity. A broad fold, widening posteriorly, extends from the 

 beaks to the hinder end. Beaks low, scarcely rising above the 

 hinge, and situated at 23 mm. from the anterior end or at 

 30/100 of the length. The sinulus is shallow, bordered in 

 front by a short, oblique line and gradually disappearing to- 

 wards the end of the dorsal margin. The form of the sinulus 

 militates against the theory that the specimen is a very young 

 one. yet the slight depth of the muscular impressions would 

 indicate that it is not fully grown. The shell is exceptionally 

 thin, so much so that it is possible to read the underlying label 

 through its substance. The posterior adductor scars are sub^ 

 sinual and even pr?esinual. Epidermis pale green, darker to- 

 wards the ventral margin and with radiating rays on the an- 

 terior half. Nacre lively iridescent, with fine, radiating rays. 

 The prismatic border is only T mm. in front, but at the hinder 

 end becomes from 6 to 8 mm. wide. 



Length 78, height in the middle 26, behind 2^ mm., which 

 is from 33/100 to 34/100 of the length, diam. 15.5 mm." (vou: 

 Thering). 



Type locality, Rio Sao Francisco, Villa Nova, State of Bahia. 

 Mycctopoda bahia von Ihering, Abh. Senck. Ges., XXXII, 



19T0, p. 122, pi. 12, figs. 3a-Z'. 



"This species stands near to M. hupeana, but dififers in hav- 

 ing the portion of the dorsal margin behind the beaks much 

 longer, which explains the longer form of the shell and the 

 more anterior position of the beaks." 



Mycf;topod.\ punctata (Preston). 



"Shell elongate, thin, covered with a pale olive periostra- 

 cum, and exteriorly sculptured with faint striae radiating from 

 the umboes ; umboes inconspicuous ; anterior end rounded, 

 gaping ; posterior end produced, acuminate below ; dorsal mar- 

 gin straight ; ventral margin slightly convex ; interior of shell 



