PELECYPODA—TELEODESMACEA. 



577 



CLXXXI. Turnus Gabb. 



Thin gaping, furrowed from beak to base by an umbonal groove 

 which appears as a ridge on the interior of the shell. Posterior to 

 this is another internal ridge, passing likewise from beak to base 

 but not evident on the surface. The anterobasal portion of the 

 shell obliquely or angularly truncate, the growth lines curving up 

 around this truncation. Burrows in wood and secretes a shelly 

 tube. Cretacic. 

 605. T. kummeli Weller. Cretacic. 



Tubes exceedingly contorted ; maximum diameter about . 3 5 inch. 

 In anterior view the shell is cordate in outline. Beaks in front 

 of middle of shell, pointed and stongly incurved. Umbones very 

 prominent. Anterior basal truncation rectangular. 



Ripleyan of New Jersey (Marshalltown-Merchantville), Texas. 



CLXXXII. Teredo Linne. 



Shell much reduced, equivalve, more or less globular, gaping 

 at both ends. Valves trilobed, with concentric striae. In interior 

 beneath the umbones is a long, narrow plate for the insertion of the 

 pedal muscles; adductor scars unequal. Pallial 

 line coincident with the valve margins. Posterior 

 portion of animal (elongated siphon) covered by 

 a long calcareous tube, which is cylindrical, 

 straight or curved. The animal bores into wood, 

 the valves occupying the bottom of the burrow 

 and connecting with the exterior by the calcare- 

 ous tube ; the external opening is protected by 

 small accessory simple spatulate valves. Juras- 

 sic-Recent. 



606. T. irregularis Gabb. (Fig. 793.) 



Cretacic. 



Tubes exceedingly contorted. Shell subglo- 

 bose, heart-shaped in outline from in front, widely 

 gaping behind, open in front. Beaks a little an- 

 terior of middle, prominent, much elevated above 

 the hinge line and strongly incurved. Tubes vary in diameter. 



Ripleyan of New Jersey (Magothy and Merchantville), Ar 

 kansas. 



FlG. 793. Teredo 

 irregularis. (After 

 Whitfield. ) 



