72 • MAZATLAN BIVALTTES 



into a tube. Tlie epidermis is extremely tliin, but important 

 to preserve the sbell, whicli soon becomes of a calcmed appear- 

 ance without at. The radiating stria become obsolete m the old 

 shells, but not so much so as in Ch. amathusia. The snraUest 

 valve measures 'OS in length : the largest specunen, long, d' 5, 

 lat. 3 "56, alt. (without spines) 2 '3. 



JT«5.— Payta, Peru, Fontaine, D'Orbigny.— Panama, rare, C. B. 

 Adams!— S&u Bias, Jay.— Mazatlan ; Lieut. Green, (G-ould 

 ms.) ; extremely abundant ; L'pool Sf Havre Coll. 

 Tablet 319 contains 3 very young valves.— 320, 4 young 

 specimens, form somewhat rounded.— 321, 3 do. adolescent.— 

 322, 3 do. adult.— 323, 3 young, slightly produced.— 324, 3 do. 

 adolescent.-325, 2 do. adult, ribs close.-326, 3 do young, 

 more produced.-327, 2 do. adult.-328, 4 young, rather flat- 

 tened, with distant laminse.— 329, 3 do. adolescent.— 330, 2 do. 

 adidt.— 331, 5 young specmiens set to shew the ventral margin 

 in different stages of growth.— 332, 4 do. adolescent.— 333, 4 do. 

 adult.— 834, 2 sp. shewing the nearest approach to Ch. amathusia, 

 and unnatural longitudinal grooves.— 335, 1 sp., ribs not foli- 

 ated ventrally.-336, 2 do., ribs flattened.-337, 1 do., strongly 

 foliaceous.— 338, 1 do., foliations semispmous.— 339, 1 sp. de- 

 formed growth.— 340, 3 do. with irregular ribs, iu all 09 

 specimens. 



102. Venus (Chione) amathusia, Phil. 



Venus amathusia, Phil. Ahhikl. p. 129, pi. 2, f.^.-p. B. Ad. 



Pan. Shells, p. 269, no. 435.— Soio. Thes. Conch, p. 709, 



pi. 154, f. 26, 27. ^ 



Chione gnidia, var. Desh. B. M. Cat. Yen. p. 133, no. 41. 

 + Chione amathusia, Desh. do. p. 132, no. 39. 

 ?= Venus canceUata, Menke m Zeit.f. Mai. 1847, p. 191, no. 



58, (non Lam.) ,^, ^ ■• 



P=Venus succincta, Val. in Jltimb. Bee. d Ohs. vol. n. 



I follow Hani. Sow. and ? C. B. Ad. in regarding this as 

 Philippi's species. It agrees exactly with the description ; not 

 with the figure. I have however a very worn young stumpy 

 specimen from S. W. Mexico, which is sufficiently like the 

 figure, especiaUy when it is remembe-ed that figures are not 

 always like the shell. I cannot say that I should have known 

 it even from Sow.'s figure, which is much better. Uesh. re- 

 cards Phil.'s species as distinct, and (with Dr. Gray) considers 

 this a variety of Ch. gnidia. What changes the creatures make 



