﻿BRITISH FOSSIL CEPHALOPODA. 215 



Distribution. — In the Bala Beds, Cymmerig Brook (2), Glyn Ceiriog (6), includ- 

 ing the variety trapezoidalis, Twll Ddu (1), Kildare (1) (the L. Hibernicus) ; also 

 Lower Llandovery, Golengoed (1). 



Nautilus (Trocholites) scoticus, Blake, PL XXIX. fig. 6, and PI. XXVIII. fig. 4. 



Type. — Kate of increase 1.45. Last whorl .37 ; the outer whorls slightly 

 overlapping. The specimen is contorted, and thus appears out of symmetry. The 

 section is a nearly uniform ellipse, with axes in the ratio of 10:9, and the long 

 diameter in the plane of curvature. There are no ribs of large size, but the whole 

 is uniformly covered by sharp riblets, which pass obliquely backwards and meet at 

 a rounded angle of 60° on the front. There are about 3 of these per line in the 

 middle of the whorl. The body-chamber leaves the coiled portion for a short 

 distance, and the shell is thickened near the aperture, which is parallel to the 

 riblets : thus it is oblique, and has a deep concavity on the front and then the shell 

 expands. No septal characters are ascertainable — though septa are present. From 

 the Bala Series, Penwhapple Glen. In the Museum of Practical Geology. 



General Description. — Only one other example (PI. XXYIII. fig. 4) can be 

 referred to this. It shows the centre to have had no vacuity, and the shell to have 

 2i whorls in a diameter of f inch. There are the fine ornaments as before, and 

 the septa grow closer towards the larger end. On the average there are about 

 22 per whorl, and they are uniformly concave. No siphuncle has been seen. 



Relations. — This specimen has been labelled Lituites cornu-arietis in the Museum 

 of Practical Geology, as the nearest ally to it among named forms. It differs? 

 however, in the absence of the large ribs. It is so like the general shape of 

 Trocholites planorbiformis that I cannot doubt its belonging to the same genus. 



Distribution. — In the Bala Series, Penwhapple Glen, Ayrshire (1) ; and in the 

 Upper Llandovery, Bogmine, Shelve. 



Group IV. Irregulares. 



Genus Trochoceras. 



Trochoceras remotum, Blake. 



Type. — The only specimen seen has its characters much concealed by an 

 encrusting material, which may be organic and spongeous. The rate of increase is 

 about 1.43, and the last whorl is .3 of the diameter. The whorls are only just, if 

 at all, in contact. There is no proof of its having been elevated, and therefore its 

 reference to the genus Trochoceras is doubtful. It is only placed there on account 



