220 SCALARIDA, 
Distr.—2 sp. Europe, Greenland. H. atomus, Phil. (1xv, 
15,16). 
Shell planorbiform, with involute spire; whorls more or less 
angulated ; mouth clasping both sides of the periphery. Oper- 
culum few-whorled, nucleus central. 
Body flattened, tentacles wanting, eyes sessile behind the head. 
Cyrcuuus, Jeffreys. 
Distr.—C. striatus, Phil. (xvi, 37). Mediterranean. 
Shell minute, discoidal; umbilicus large, profound. Oper- 
culum multispiral, corneous. 
DiscoHeLIx, Dunker. 
Syn.—Orbis, Lea (not Blainv. or Lacep.). Bifrontia, Desh. 
Tlaira, H. and A. Adams. Platystoma, Hornes. 
Distr.—D. zanclea, Phil. (xv, 17, 18). Fossil. Silurian, 
Liassic, Cretaceous, etc. 
The genus was proposed for a liassic, discoidal shell, composed 
of quadrangular whorls, carinated and more or less crenulated 
on the upper and lower edges of the back, on which the striz of 
growth are insinuated backwards. 
OPHILETA, Vanuxem. 
Syn.—Cyclogyra, Wood. Planaria, Brown. Discohelix, Adams 
and Chemn. 
Shell planorbiform, discoidal, whorls numerous, slender, in 
contact. 
Proposed for a palseozoic fossil of New York (0. levata, Hall, 
Ixv, 19); to which may be added the recent Discohelix foliacea, 
Phil. (Ixiv, 88, 89). 
EccyntiompHauus, Portlock, 1843. 
Syn.—Serpularia, Roemer. Phanerotinus (partim), Sowb., 
1842. 
Distr.—Fossil. Paleozoic,a few species. LH. serpula, Kon. 
(ixv, 20). 
Shell discoidal, whorls few, in the same plane, widely disso- 
lute; flattened above, rounded beneath. 
Famity SCALARID A. 
Characters those of the only genus. These mollusks are closely 
related to the Ianthine, of which they may be regarded as 
creeping representatives, on the one side, and to Turritella as 
well, by the form of their shell. Dentition xi, 36-38). 
Scabaeia, Lam. 
Etym.—Scalaris, like a ladder. Wentle-trap. 
Syn.—Sthenorytis, Compsopleura and Scalarina, Conr. 
