CTETOCEEATIT)-E. 
311 
number of extremely fine longitudinal striae, and these are crossed 
at right angles by a series of equally fine transverse striae, which 
together form a very dehcate network, like a spider’s web, hence 
the name of the species. 
Remarics. The name of this species was changed by its author 
from reticulatum to arachnoideum, the former name having already 
been bestowed by Phillips upon a Devonian speciesh 
Horizon. Calschiste de Tournai (Assise i. e) ; = Carboniferous 
Limestone. 
Locality. Tournai, Belgium. 
Eepresented in the Collection by a single example. 
c. Mediogastric. 
Cyrtoceras (Meloceras) cinctum, Munster, sp. 
1843. Cyrtocera cincta, Miinster, Beitrage z. Petref. Heft i. p. 57, 
Taf. ii. f. 4. 
1843. Denfalium cinctum, de Koninck, Descr. des Anim. Foss, du terr. 
Carb, de la Belgique, p. 318, pi. xxiii. f. 3. 
1844. Orthoceras subcenfrale, de Koninck, ibid. p. 514, pi. xliv. f. 3. 
1844. Cyrtoceras cinctum, de Kouinck, ibid. p. 526, pi. xlviii. f. 4. 
1849. Aploceras cinctum, d’Orbigny, Prodr. de Paleont. Stratigr. vol. i. 
p. 112. 
1849. Ortlioceratites subcentralis, d’Orbigny, ibid. p. 113. 
1852. Cyrtoceras cinctum, G\QhQ\, Fauna derVorwelt, Band iii. Abth. i. 
p. 203. 
1852. Orthoceras suhcentrcde, Giebel, ibid. p. 252. 
1880. Cyrtoceras cinctum, de Koninck, Faune du Calc. Carbonifere de 
la Belgique, p. 29, pi. xxxiii. fi*. 12, 13. 
Sp. Char. Shell very elongated, regularly curved, slowly in- 
creasing in diameter, transverse section perfectly circular. Septa 
distant from each other about 2 lines, where the shell has a 
diameter of 6 lines. Body-chamber large, occupying about one 
third of the total length of the shell. Siphuncle very slender, 
almost filiform, situated in the line of the ventro-dorsal diameter at 
a distance of ^ of that diameter from the margin. Surface 
ornamented with numerous acute riblets, separated from each other 
by spaces as wide as themselves ; they are generally, but not always, 
parallel with the plane of the septa. 
Remarics. A portion of the body-chamber of this species was 
referred by de Koninck (in 1844) to the genus Dentalium, and 
another fragment was erroneously ascribed to Orthoceras sub- 
centrale, de Kon. 
1 Pal. Foss, of Cornwall, Devon, and West Somerset, p. 117, pi. xlviii. f. 224. 
