26 CONCHOLEPAS. 
would be more properly confined to that portion of the inner-lip 
which is seen below the body whorl, over which the remainder 
of the inner-lip is frequently spread. In fig. 431, the anterior 
termination of the Columella is indicated by the letterc. The 
axis is an imaginary line drawn strictly through the centre of 
the whorls, whether their inner edges form a solid column or 
not. 
COLUMELLA’TA. (Columellaires, Lam.) A family belong- 
ing tothe second order of Trachelipoda, Lam, containing the 
genera Columbella, Mitra, Voluta, Marginella and Volvaria. 
To which may be added other genera enumerated in the expla- 
nation of figures 430 to 439. 
COMPRES'SED. Pressed together, or flattened. Application 
the same as incommon use. A Patella may be described as a 
vertically compressed cone. A Ranella, on account of the two 
rows of varices skirting the whorls, appears as it were laterally 
compressed. 
CONCAMERA'TIONS. (Con, with; camera, chamber.) A series 
of chambers joining each other, as in Nautilus, Spirula, &c. 
CONCEN’TRIC. A term applied to the direction taken by the 
lines of growth in spiral and other shells. Every fresh layer 
of shelly matter forms a new circle round an imaginary line 
drawn through the centre of the spiral cone, down from the 
nucleus. When the edges of the successive layers are marked 
by any external characters, the shell is said to be concentrically 
striated, banded, grooved, costated, &c. A fine illustration of 
the latter is to be seen in the Scalaria, or Wentletrap. Fig. 351. 
CONCHA‘CEA. Bl. The eighth family of the order Lammelli- 
branchiata, Bl. The genera described in this family are divided 
into three sections, First, those which are regular and have 
distant lateral teeth, Cardium, Donax, Tellina, Lucina, Cyclas, 
Cyprina, Mactra, and Erycina. Second, Those which are regu- 
lar, and have no distant lateral teeth, Crassatella, Venus. Third, 
Those which are irregular, Venerupis, Coralliophaga, Clotho, 
Corbula, Sphzenia, Ungulina. 
CONCHA’CEA. Lam. _ A family of Lamarck’s order Conchi- 
fera Dimyaria, thus described: ‘ Three cardinal teeth, at least 
on one valve, as many or fewer on the other, with lateral teeth 
sometimes. This family is divided into two groups, first, Con. 
ques Fluviatiles, containing the genera Cyclas, Cyrena, Gala- 
theea ; second, Conques Marines, containing Cyprina, Cytherea, 
Venus, Venericardia, and others, enumerated in explanation of 
figures 111 to 121. 
CONCHO’'LEPAS. Lam. (Concha, a shell; lJepas, a stone or 
rock.) Fam. Purpurifera, Lam. Entomostomata, Bl. Deser. 
Oval, imbricated, thick; with avery short spire and large oval 
patelliform aperture, terminating anteriorly ina slight emargi- 
