42 CLASS I. TROPIOPODA. ORDER I. BIMUSCULOSA. 



Family 3. SOLENACEA. 



Testa transversim elongata, partibus testaceis accessoriis nullis, utraque 

 extremitate plerumque hians ; interdum appendice testacea fixa sub 

 umbone utriusque valvae. 



The shell of the Solenacea, though generally elongated or cylindrical, 

 varies considerably in form, as also in the number and position of the 

 teeth, which in some instances are wholly wanting. It is generally gaping 

 at both ends, the ligament is external, and in some species there is a fixed 

 testaceous appendage under the umbo of each valve, called the fulcrum. 



The Solenacea are not lithophagous, nor have they the accessory 

 pieces of the Pholadaria ; but if any analogy may be traced in their 

 habits, it is because they bury themselves to a considerable depth in the 

 sand. We include eight genera in this family, as follows : 



solen. solemya. 



solecurtus. solenella. 



Panop.ea Glauconome. 



Glycimeris. Pholadomya. 



SOLEN, Linnaeus. 



Testa sequivalvis, linearis, egregie insequilateralis, utraque extremitate 

 hians ; antica brevissima, subtruncata, vel subrotundata. Dentes 

 cardinales parvi, varii, posterior bifidus, plerumque recurvus ; inter- 

 dum dens lateralis, elongatus. Impressiones musculares distantes, 

 antica ligulata sub vel post umbonem posita, postica irregularis, 

 subovalis ; impressio muscularis pallii rectiuscula, longissima, 

 postice bifurcata. 



