102 AMERICAN JOURNAL 



The genu?! Tcrchriitula of Llhwyd, who was not a binomial 

 author, was adopted by Miiller (Prodr. Zool. Dan. ITTG, pp. 

 xxxi and 249). although not in the restricted sense in which it 

 is at present employed. Ilis Tcrebratuhv embraced several spe- 

 cies nuw ilistributod in difterent genera. In 1799, Lamarck, in 

 his Prodr. Nouv. Class, des Coquilles, adopted the name, taking 

 T. perovah'ft, Sby., as his type. This example has been followed 

 by almost all subsequent authors. The generic term Anomia 

 used for species of this family by Bolten (1798), Linnreus, and 

 other authors, has in modern times, with equal unanimity been 

 applied to a genus of Lamellibranohiate mollusca. 



The type most commonly cited for the genus is the recent 

 Tcrebratula vitrea of Born (= ^-l^ow/a terebratula, hm. Syst. 

 Nat. 1153, and trn/phus I'itrea, Megerle, Berl. Mag. 1811, p. 

 64:), which inhabits the Mediterranean and is found fossil in the 

 Pliocene deposits of Sicily. 



Terebratula unguicula, Cpr. 



T. unguicuJa, Cpr., Proc. Zool. Soc. Feb. 14. 1865, figs. 1 to 

 4, p. 201. Cooper, Geogr. Cat. of Cal. Mollusca. p. 3, 

 No. 3. 



ITab. San Diego, 6 fm. ; Monterey, 20 fm., Cooper. Van- 

 couver Id., Forbes. Sitka, under stones at low water ; Unga 

 Id., 4 fms., Dall. 



This remarkable and very distinct species is provided in the 

 young state with strong, radiating, simple ribs, and in this con- 

 dition the hi^mal valve resembles, exteriorly, a small J^ecten. In 

 older speciuiens the ribs bifurcate and become less pronounced, 

 and the resemblance to a young 2\-reb}'ati(Iina eaput-serpentis 

 becomes more marked. The principal difterences are that the 

 Terebratuhi is rather the wider, and the intercostal spaces are 

 more channelled than in the TerebratiiUna. Even these differ- 

 ences may not be constant in a large number of specimens. The 

 broad incomplete loop, of course, is abundantly sufficient to 

 identify this species. The umbo of the neural valves is sharply- 

 pointed in perfect specimens ; the foramen is large and incom- 

 plete, the area smooth and very short ; there is no deltidiura, 

 and the pedicel is usuallv stout and short. 



Smithsonian Cabinet. 'l4.789, 14,892, 15,264. 



Xo. 16,232, a single valve from Neeah Bay, appears to be 

 Terebratella eaun'na. Gould, jun., worn. 



