SX STNOPSISOF 



Strophitus, Raf., emend. Gills attached; eggs received in the whole extent of the outer gill; 

 anal opening not fringed. [Anodonta undulata, Say.) 



Anodonta, Brug. Gills free; eggs throughout the gill; anal opening not fringed. {Anodonta 

 Benedidensis, Lea.) 



Soon after the appearance of Dr. Stimpson's publication fi'om Prof. Agassiz's 

 MSS. I tabulated his divisions and those of Prof. Troschel for my own use. To these 

 I occasionally added notes, and I produce the tables here for reference. 



TEOSCHEL'S DIYISIONS OP THE FAMILY UNIONIDJ^.i 



Diagnosis of the Family of tJNioNrD.E. — Shell with epidermis; without emargination in the mantle; two muscles, the anferior of which makes 

 commonly three impressions in the shell ; one exterior ligament; mantle without branchial and anal tubes, and without retractile muscles ; two extei'ual 

 and two inlernal mouth lips which are large and rounded, and internally perpendicularly striate; two branchiaj oa each side, united to each other 

 behind the foot for the whole length ; branchial filaments not separate. All live in fresh water. 



^Unio. Retz, 

 tnmidus. 



Mouth Lips. 

 Wider than long, 

 united to mid. post. 



Mantle. 

 I entirely open. 



BranchicE. Foot. 



Oater united to mantle to ex- Tongue -shaped, thick; pro- 



treraity. Inner not united to duced anteriorly, 

 foot. 



Margaritana. Sch. 

 margaritifera. 



Wider ihan long, 

 uniied to % post mar- 



Outer is free posteriorly. In- Tongue-shaped, thick ; some- 

 ner united to foot anleriorly, what produced anteriorly, 



but free the greater part. 



Hyria. Lam. 



syrmutophora. 



Castalia. Lam. 



Wide as long, not Margin inf. open. Post, closed Outer united to the mantle to Tongue-shaped, thick; some- 

 united, to make branchial and anal extremity. Inner united to what pioduced anteriorly, 

 aperture. the foot. 



Little wider than long. Margin inf. open. Post, closed Outer united to mantle to ex- Tongue-shaped, thick; sorae- 



to make branchial and anal tremity. Inner ? what produced anteriorly. 



Dipsas. Leech. 



SAnodonta. Lan 



cellensis. 



Iridina. Lam. 

 cailestis. 



Spatha. Lea. 

 rubens. 



Animal unknown. 



Wider than long, 

 united to middle of 

 posterior margin. 



Longer than wide, 

 nut united. 



Longer thai 

 not uniied. 



Mycetopus. D'Orb. Longer than wide. 



' Wiegman's Archives^ lSi7, v. 13. 



Margin entirely open. 



Outer united to mantle to ex- Tongue-shaped, thick ; sorai 

 tremity. Inner not united to what produced anteriorly, 



foot. 



Margin united as far as the Outer united to mantle to ex- Tongue-shaped, thick ; some- 

 foot, so that branchial and tremity. Inner entirely unit- what produced anteriorly. 

 anal apertures are closed. ed to foot. 



Margin closed behind, so that Outer united to mantle to ex- Tongue-shaped, thick; some- 



the bran, and anal apertures tremity. Inner not uniied to what produced anleriorly. 



are closed ; entirely open on foot. 

 the under margin. 



Margin open to anal aperture, Outer enfivply united. The Produced and widened into a 



which is closed. inner 'i knob. 



^ The genera Unio and Anodonta are described exactly the same ! ! 



