- 96 - 



Barb at la ( Aoar ) reticu].ata Gmelin, Dall, 1915, Bull. U. 3. Nat,, 

 Ittas., no. 90, p. 120/ 



Desoription .- "A. testa sulDrhomTDoiclea dec-ussatim striata 

 alba; natibiis approximatis, valva eordata." (Graelin, 1791) 



The Bowflen speciniens are small, thick-shelled, sxibrhomboid- 

 sl, moderately inflated; rounded anteriorly, obliquely truneated 

 posteriorly; umbones lovr, broad, strongly incurve'^, prosogyrate, 

 placed at about the anterior third of the length; posterior ridge 

 well defined, subangiilar; external surface sculptured with strong, 

 somewhat irregular concentric riri es, separate-' by deeply- channel- 

 ed narrovi; grooves, and less prominent, but more numerous, radiat- 

 ing ribs; the concentric rids-es often giving an imbricated effect, 

 especially on the posterior ridge and occasionally shnv/ing super- 

 imposed fine concentric striae; posterior slope usually feebly 

 sculptured; cardinal area narrow, excavated, becoming slightly 

 wider in front of the umbo, transversely striated; hinge relat- 

 ively short, gently arched; median teeth short and irregular or ab- 

 sent, posterior teeth more numerous than the anteri-r and more 

 oblique; muscle scars pnominent, the edges beirf: raised above the 

 surface of the shell; inner margin of the valves finely and irres- 

 ularly crenulated. 



Diniensions .- Length, 19 mm.; alt. 11 mm.; semidiam, 5 mjn. ; 

 length of hinge, 10 mm. 



