ART. 11 ANATOMY OF FRESH-WATER MUSSELS — REAEDON 11 



definite beak sculpture so characteristic that it is a reliable means 

 of classification. In E. produdus the beak sculpture consists of 

 strong, longitudinal, corrugated ridges. 



The posterior ridge is well developed, curved down the middle, 

 ending behind the center in a long, drawn-out point near the median 

 line with the point often turned up. From the beaks in a radial 

 direction are heavy, irregular growth lines. 



The interior of the shell is iridescent and is purplish or whitish and 

 shows muscular scars. In the left valve on the dorsal surface are 

 two stumpy pseudocardinal teeth and two strong lateral hinge teeth. 

 In the right talve is one pseudocardinal and one lateral tooth. 



MANTLE 



Plate 5, fig. 3 



The mantle edge at the dorsal mantle aperture and the siphons 

 is pigmented, but not heavily so. The dorsal mantle aperture 

 extends almost the length of the* posterior adductor muscle, while 

 the connected portion between this aperture and the exhalent 

 siphon is about as long as the inhalent siphon. Both siphons bear 

 tentacles. The body is slender and elongate. 



GILLS AND REPRODUCTIVE SYSTEM 



Plate 5, figs. 6, 7, and 9 



The gills are very much elongated, with the outer pair serving as a 

 marsupium and forming a smooth pad when filled with embryos. 

 The glochidia are bookless. 



BEAK SCCLPTURE 



Plate 5, fig. 5 

 EXPLANATION OF PLATES 



Figure 1 



1. Hinge line. 5. Anterior end. 



2. Beaks. 6. Posterior end. 



3. Growth lines. 7. Ventral margin. 



4. Dorsal margin. 



Figure 2 



1. Lateral hinge teeth. 5. Anterior retractor muscle scar. 



2. Posterior retractor muscle scar. 6. Anterior adductor muscle scar. 



3. Posterior adductor muscle scar. 7. Protractor pedis muscle scar. 



4. Pseudocardinal tooth. 8. Pallial line muscles scar. 



Figure 3 



1. Anterior retractor muscle. 9. Renal org'an. 



2. Anterior adductor muscle. 10. Posterior retractor muscle. 



3. Protractor pedis muscle. 11. Dorsal mantle aperture. 



4. Pallial line muscles. 12. Posterior adductor muscle. 



5. Foot. 13. Exhalent siphon. 



6. Pericardial gland. 14. Inhalent siphon. 



7. Ventricle. 15. Dorsalmantle muscles. 

 >^. Left auricle. 



