120 MAZATLAN BIVALVES 



Hab. — Mazatlan ; jun. abundant, rare adult, among sea weeds 

 on Chamne, SpondyH. Ostreae, Patella?, &c., or in the cavities 

 of dead Litlioi^hagi or Balani ; L'pool Sf Havre Coll. 



Tablet 540 contains 5 pairs and 6 pairs of valves, smooth 

 form. — 541, 7 pairs and 6 pairs of valves, slightly Urate. — 542, 

 11 pairs and 7 pairs of valves, lirate, jun. — 543, 7 pairs do. 

 adult. — 544, 2 pairs and a valve strongly lirate. — 545, 2 sp. in 

 crevices of Balanus and Lithophagus ; another Balanus has a 

 crab in situ ; off Patella Mexicana. — 546, a group in situ 

 among Balani, on M. palliopunctatus. — 547, 2 sp. one with the • 

 surface in concentric layers, like Crepidida Lessouii ; the 

 other with young Nullipore. 



Tablet 548 contains 5 pairs and 4 pairs of valves, greenish 

 var., smooth form. — 549, 7 pairs and 4 pairs of valves, finely 

 Urate.— 550, 4 pairs and 1 pair of valves, strongly liratt^— 551. 

 1 large valve, flat and broad. 



Tablet 552 contains 3 pau's and 2 valves, probably belonging 

 to this species. 



Genus SEPTIFEE, Bed. 



Vide Dimlc. Com. Sep. et Dreis., Marburgh, 1855. — Tichogonia. 

 pars, Rossmassler, 1835. 



169. Septifee Cumingii, Eecl. 



Bunker, 3Ionog. Sept. p. 8, no. 18. 



The few specimens found are too young to identify with 

 accuracy. They are covered with fine, granulose ribs, with 

 rather long bristly hairs rising up between. The umbonal 

 plate is scarcely perceptible in the smallest shells. Hinge lino 

 crenate, as in M. multiformis. They closely resemble the 

 young of S. bilocularis, but geographically agree better with 

 the species quoted. The largest specimen measures only -IG 

 in length. 

 j[f^7j —Panama, Mus. Cuming.— Mazatlan ; extremely rare, 



jun. on Spondylus ; IS pool Col. 



Tablet 553 contains 3 pairs of different ages. 



Genus MODIOLA, Lam. 



Volsella, Scopoli, 1777.— Modiola, Lam. 1801.— Modiolus, 

 Bhso, 1826. 



