22 TJMBEACULtTM. 



author of the latter remarks that the shell is angulated at the sides 

 and sculptured by very fine arched striae descending to the lateral 

 angulations. "The aperture is narrowly oval-oblong, with trun- 

 catedly rounded ends ; each lip has a median curvature bounded 

 on each side by a broad insinuation." The apex is in nearly all 

 cases well preserved. The shell is very variable in length, some 

 specimens being much narrower in proportion than others ; such 

 differences may be adjusted, however, in reviewing a large number, 

 and are not of specific value. 



Dimensions. — Length 7 mm.; breadth about Hmm. 



Form, and Loc. — Eocene : Muddy Creek, Victoria. 



G. 9310. Several specimens. Purchased. 



Family TJMBRACULIDJE. 



Genus UMBRACULUM, Schumacher. 



[EssaiNouv. Syst. Habit. Testaces, 1817, p. 177.] 



" Ombrelle," Lamarck, Cours Zool. 1812, p. 114. 

 Umhrella, Lamarck, Anim. sans Vert. t. vi. 1819, p. 339. 

 Gastroplax, Blainville, Diet. Sci. Nat. t. xviii. 1820, p. 176. 

 Omhrella, Blainville, Diet. Sci. Nat. t. xxxii. 1824, p. 267. 

 Umbella, D'Orbigny, Moll. Cuba, t. i. 1841, p. 115. 

 Operculatum, H. and A. Adams, Gen. Bee. Moll. vol. ii. 1854, 

 p. 41. 



Shell orbicular, broad, patelliform, apex very small ; ornamented 

 exteriorly with concentric lines of growth ; internal surface with 

 concentrically undulating striae radiating from the centre to the 

 circumference of the shell, but more prominent towards the centre. 



The genus is generally called Umhrella, but, as the synonymic 

 references above indicate, Umhraculum has priority. The designa- 

 tion "Ombrelle," if it were not a mere list name, could not stand, 

 in consequence of its being French, and not Latin. The term 

 Operculatum created by Linnaeus ^ and brought on by the brothers 

 Adams cannot be accepted, first because it was not made in a 

 binomial sense, and secondly as it was proposed prior to the date 



1 Mus. Tess. 1753, p. 116. 



