CERITHIUM. 167 



The Comma-Group. 



This name is applicable to a group of shells which are rare in the Inferior 

 Oolite of this country, but not so unfrequent in the Bajocian of Normandy. There 

 can be very little doubt that they are included by Deslongchamps (op. cit., pi. xi, 

 figs. 64 — 66) as forming part of his var. a, " Melania scalariformis, Deshayes." 

 The other part of var. a, viz. fig. 63, is the basis of Cerithium subscalariforme, 

 D'Orb. As this name, then, has been used for quite a different species of Cerithium, 

 we must fall back upon Minister's name. The forms described below as distinct 

 species are probably little more than varieties ; but as, owing to their rarity in 

 England, the missing links are not forthcoming, I propose to describe some two or 

 three different forms for which more or less appropriate foreign names may be 

 found. 



93. Cerithium comma, Miinst., 1844. Plate X, fig. 2. 



1842. Melania scalarifoemis, Desl. (pars). Deslongchamps, Mem. Soc. Linn. 



Norm., vol. vii, pi. xi, fig. 64. 

 1844. Ceeithium comma, Munst. Goldfuss, Petr., t. 173, fig. 14. 

 1850. Synonym Cerithium opis, D'Orb. Prod., vol. i, p. 271. 



Bibliography, Sfc. — The following is the original description by Goldfuss : 

 " Turrited, with twelve to fourteen whorls, quadrangular, subquadrate, beset in the 

 upper part with numerous wrinkles. These wrinkles form at the suture elongated 

 knots, and run off into feeble, somewhat crooked ribs, which split up, and terminate 

 at the lower margin in a row of very fine knots. At one place are observed obscure 

 traces of faint spiral lines." The length of this specimen was about 20 mm. 



Description of an English specimen : Length 30 mm., width 9 - 5 mm. Spiral 

 angle about 20°. Shell sharply turrited. Spiral angle regular, whorls numerous, 

 about sixteen, flat or slightly concave, rather narrow, and increasing by steps. The 

 spiral strice are very fine and numerous ; longitudinals bold and prominent on the 

 posterior half of each whorl, having a spinous projection upon the upper border. 

 About half way across the whorls the longitudinals become attenuated, usually 

 bifurcating and curving from right to left, so as to give the appearance of a 

 comma. 



The body- whorl is less than one-third the total length of the shell; the 



