CYKIOCEEATID^. 
307 
1880. Cyrtoceras cornu, de Koninck, Faune du Calc. Carboni:fere de la 
Belgique, p. 26, pi. xxxvi. fif. 5-8. 
Sj). Char. Shell of medium size, strongly curved ; initial point 
obtuse, and showiug the cicatrix. Bate of increase about 1 in 4. 
Transverse section circular. Septa rather widely separated from 
each other, undulating, rather deeply concave. Siphuncle nummu- 
loidal, situated at a little distance from the ventral border, in the 
median line. Test thin, its surface perfectly smooth. 
RemarJcs. To this species I have referred several examples (in- 
cluding the specimen figured by Sowerby) which agree tolerably 
well with de Koninck’s description, though he does not mention the 
undulation of the sutures, which is a marked feature in the 
specimens before me. The body-chamber of J/. cornu was unknown 
to de Koninck, but it is well shown in one of the lluseum specimens^ 
in which it occupies at least half the entire length of the shell. 
Horizon. Calschiste de Tournai (Assise i. e) ; = Carboniferous 
Limestone. 
Localities. Bntish. Dublin, Kildare. — Foreign. Belgium. 
Represented in the Collection by several good specimens, in- 
cluding the one figured by Sowerby {loc. cit.), and now contained 
in the “ Sowerby Collection.’’ 
Cyrtoceras (Meloceras) acus, de Koninck, sp. 
1844. Cyrtoceras uyiguis, de Koninck, Descrip, des Anim. Fossiles de 
la Belgique, p. 524, pi. xlvii. f . 8 « (excl. S’. 8, h, c), pi. xlviii. f. 6 h 
(excl. ff. 6, a, c). (A’o^ of Phillips.) 
1876. Cyrtoceras unguis, F. Roemer, Lethaea Palaeozoica, Taf. xlvi. f 4. 
1880. CyHoceras acus, de Koninck, Faune du Calc. Carbonifere de la 
Belgique, p. 28, pi. xxxv. ff. 6, 7, pi. xxxvi. f. .3. 
F>p. Char. Shell slightly curved at the apical extremity, straight 
above ; obtusely pointed at the apex, which shows traces of the 
cicatiix in one of the specimens. Transverse section elliptical, the 
ratio of the two diameters as 7:9. Rate of increase measured in 
the plane of the greater diameter 1 in 2 ; some specimens, however, 
dilate less rapidly than this. Septa numerous, 40 having been 
counted in a specimen measuring 3 inches o lines in length. 
Siphuncle near the convex border ; its elements nummuloidal. 
Surface of the test smooth, but traces of the original colour pattern 
are often preserved, consisting of zigzag bands alternately light 
and dark-coloured 
^ Eegistered Ko. 30257. ^ Registered Ao. 43837. 
® These are well shown in the specimen in the Museum Cofiection, registered 
No. 64837. 
