panamic-pacific pelecypoda 517 



Explanation of Plate 44 



Figure Page 



1. Tirela (Pachydesma) argenta (Sowerby) 270 



Enlargement of hinge and exterior of a left valve, length 50.5 mm. 

 Buenaventura, Colombia. PRI 25716. 



2-2a. Tivela (Planitivela) nndulata (Sowerby) 267 



Fig. 2, length 58 mm.; Fig. 2a, length 53 mm. Charapota, Ecuador. 

 PRI 25717. 



3. Tivela (Tivela) byroneiisis (Gray) 267 



Length 46 mm. San Pedro, near Manglaralto, Ecuador. PRI 25718. 



4-4b. Tivela (Planitivela) liians (Philippi) 270 



Figs. 4, 4a, length 60.6 mm.; Fig. 4b, length 60.6 mm. Negritos, Peru. 

 PRI 25719. 



5-5a. Tivela (Planitivela) plannlata (Broderip and Sowerby) 269 



Fig. 5, enlargement of hinge and exterior of a right valve, length 60.1 

 mm. San Pedro, near Manglaralto, Ecuador. FRI 25720.; Fig. 5a. 

 length 61.7 mm. Boca Pan, Peru. P"RI 25721. 



6-6a. Tivela (Tivela) byronensis (Gray) 267 



As radiafa Sowerby after Romer. 



7. Tivela (Tivela) byronensis (Gray) 267 



As radiata, British Museum (Nat. History) 



8-8a. Tivela (Tivela) byronensis (Gray) 267 



Fig. 8, holotype of T. radiata, British Museum (Nat. History) ; Pig. 

 8a, paratype of T. radiata, British Museum (Nat. History). 



9-9a, Tivela (Tivela) delessertii (Deshayes in Sowerby) 268 



Fig. 9, length 29.2 mm.; Fig. 9a; length 26 mm. Acapulco, Mexico. 

 PRI 25722. 



