ORTHOCERAS PKRELLIPTICU.M. 23 



agreeing iu the character of its ornamentation with the latter, 0. lanUldrlatuin is 

 in its shape and septation more akin to 0. Sollasl, horn which, however, it sepa- 

 rates itself by its much finer ornamentation and larger siphuncle. On the whole 

 it is a fairly well-marked species. It has been found up to the present time only 

 in the Cork district. 



Locality. — Little Island, near Cork. 



Orthocekas pkrkllipticum (.1. H. Fuord), F. iPGoij. Plate VIII, figs, o" — c 



lSi4. Ortiiockras (Loxoceuas) distans, F. M'Coy. Synojisis of tlie C'liar. of 



tlie Carb. Liraest. Foss. of Ireland, 



p. 8, pi. iv, fig. 1 (not of Sowerby). 



1888. — PEHELLiPTicuM, A. H. Foord. Cat. Foss. Ceph. British 



Museum, pt. 1, p. 104. 

 1896. — — {A. 11. Foord), M'Coy. Ueber die Ortho- 



ceren des Kohlenkalks (Carbouiferous 

 Liraestoue) vou Irluud. . . . In- 

 augural-Dissertation zur Erlaogung der 

 Doktorwiirde . . . der Kgl. bayer. 

 Ludwig-Maximiliaus-Universitat zu Miin- 

 chen, p. .30. 



Descrijjtion. — Shell of medium size, straight, rate of increase rapid, l)eiug at 

 the rate of 1 : 5. Section elliptic, the ellipticity probably at least in part caused 

 by rock-pressure ; the proportion of the two diameters in the type specimen as 

 12 : 8. Body-chamber unknown. Septa undulating, rather widely separated 

 (hence M'Coy's name), distant from each other 6 mm. where the diameter of the 

 shell is 18 mm., the space between them increasing to 8 mm. where the diameter 

 of the shell is 26 mm. Siphuncle central or nearly so (PI. VIII, fig. 3 h), its 

 structure unknown. Shell thin, ornamented with very fine, upwardly imbricating 

 strige, arranged with approximate regularity, running obliquely across the surface 

 of the shell. Six or seven of these striae occupy the space of 1 mm. When 

 highly magnified (PI. VIII, fig. 3 c) they are seen to be of unequal size, though 

 their general aspect when looking over the surface of the shell with a haud-leus 

 gives the impression of their being fairly regular. 



Affinities. — Its elliptical form and high rate of tapering enable this species to 

 be readily distinguished from 0. multistriatum. These features exist in all 

 specimens to which I liave had access, including the type specimen contained iu 

 the Dublin Museum of Science and Art (Griflfith Collection), and others iu the 

 general collection in that museum ; also the one figured, which is from the museum 

 of Queen's College, Cork. It is easily distinguished from 0. Clanense and 

 0. Sollasi by its much finer sculpture, added to the characters mentioned above. 



