MAZATLAN BIVALVES 17 



in a position to do so. Hinge teeth, 1 in each valve, rarely 

 seen in adult. 



Largest specimen measures long. "63, lot. 1*17, alt. '47, 



A broad flat sp. '4, '68, '24, 



A long narrow one '3, '66, '2, 



Smallest '02, '04, '015. 



Hob. According to Forbes, Atlantic Ocean, Boreal Seas, 

 Africa, China, Australia. Canaries, Webb fy Bert helot, B. M. 

 Cat. Can. Moll. p. 22, no. 195. New Zealand, Capt. Stokes, 

 B. M. 8. solida : Clefts of rocks, 18 fm. St. Elena, Cuming : 

 Peru, Lima, Callao, D'Orligny, B. M. Cat. p. 58, no. 510. 

 S. distorta, Say, Rhode Is. Jay. 8. Pholadis, Sea of Okotsk, 

 Middendorf. Mazatlan ; in Spondylus Lamarckii, nestling in 

 crevices and burrows, also in Chamee and Patella Mexicana, 

 very rare adult, not common jun. ; L'pool fy Havre Coll. 

 Fossil, Crag, &c. ; very large in the pleistocene beds at Ud- 

 devalla, Sweden, E. D. D. 



Tablet 60, 6 young valves. 61, 1 valve and 6 pairs various 

 ages and shapes. 62, 1 specimen bored into, and the valves 

 cemented open by tube of borer : also 2 fragments to shew 

 ligament. 63, A young specimen in hole of Lithodomus cau- 

 digerus in Imperator unguis. 64, A specimen in situ in a Yer- 

 metus, off back of Spondylus. 



FAMILY PETRICOLnm 

 GENUS PETRICOLA, Lam. 



-f 24. PETRICOLA EOBUSTA, Sow. 



Proc. Zool. Soc. 1834, p. 4$ Sow. Thes. Condi, part xv. p. 775, 

 no. 14 ; pi. clxvi. f. 16, Vl.Mwller, Syn. Moll. p. 229, no. 9. 

 Philippi in Zeit. fur Malac. 1848, p. 163, no. 33, quasi sp. 

 nov. : edidit Desk, in JB. M. Cat. Veneridce, &c. p. 210, no. 10. 



? = P. bulbosa, Gould's plates, ms. 



The name of this shell, which was well described by Sow. in 

 1834, was appropriated by Philippi in his 3rd Century of new 

 shells for a supposed new species ; which turns out fortunately 

 to be a small specimen of Sow.'s species, and thus confusion of 

 synonymy is unexpectedly avoided. Deshayes has unfortu- 



