No. 2314. 



LIST OF RECENT BRACHIOPODA—DALL. 



275 



Cat. No. 



5962 

 173783 



Locality. 



Cape Palmas (types) . 

 West Africa 



Collector. 



U. S. Expl. Exp... 

 Sowerby 



Number 

 of speci- 

 mens. 



Genus DISCINISCA Dall. 



Discinisca Dall, Bull. Mug. Comp. Zool., vol. 3, No. 1, p. 37, 1871, type, D. 

 lamellosa Broderip. 



DISCINISCA LAMELLOSA Broderip. 



Orbicula lamellosa Broderip, Proc. Zool. Soc, 1833, p. 124; Trans. Zool. Soc, vol. 



1, p. 142, pi. 23, fig. 2, 1835. 

 Discina lamellosa S. P. Woodward, Man. Moll., p. 336, figs. 160-162, 1856. 

 Disdnisca lamellosa Dall, Bull. Mus. Comp. Zool., vol. 3, No. 1, p. 41, 1871. — 



Davidson, Mon. Rec. Brach., pt. 3, p. 197, pi. 26, figs. 1-8, 1888. 



Type locality. — Iquiqui, Bay of Ancon, Peru. Ciiming. 



Cat. No. 



173629 

 173630 

 110740 



17826 

 131040 

 102026 

 217568 



59568 



Locality. 



Peru 



Peru 



Off Peruvian coast 2,845 fathoms (dead) 



Callao, Peru, 1. w 



Arica, Peru 



Callao, Peru 



Peru 



Valparaiso, Chile 



Colleetor. 



Flower 



Jeffreys 



U'. S."Expl' Exp."."." 



Chamberlain 



Stearns 



S. Smith 



Stearns 



Number 

 of speci- 

 mens. 



1 

 1 



1 V. 



Many. 



10 



4 



2 



2 



The Disciniscas are naturally divided into three groups as follows: 



A. Large, lamellose, flexible, without radiating sculpture. Ex- 

 amples: D. lamellosa, D. laevis. 



B. Large, less lamellose, with feeble irregular radiations, more 

 solid. Examples: B. strigata, D. cumingi. 



C. Small, with regular radiating sculpture, not lamellose, solid. 

 Examples: D. stella, D. antillarum. 



Groups A and B are confined to the western coasts of the Americas ; 

 group C to the east coast of Asia and associated islands and the shores 

 of the tropical Atlantic. 



The discrimination of the species, especially if the valves are a little 

 worn, is not always easy, but the outside sculpture of the lower valve 

 and the form of the peduncular orifice afford excellent and easily 

 recognizable characters. They have also the advantage of being less 

 liable to wear and incrustation than the upper valves. 



In the case of D. lamellosa, there is a very short groove at the center 

 of the valve suggesting a closed central pedicel opening in the very 



