On the Fossil Fishes of the Carboniferous Limestone Series of Great Britain. 455 
Helodus clavatus, Davis. 
(Pb IUIDG, ies 1, Gp) 
Teeth, long, club-shaped, sinuous in outline, broadly expanded at one end, tapering 
to a fine point at the other. Length 1-2 inch, breadth ‘35 inch, height of crown 
equal to the breadth. Crown, highest point occupies a position about one-third 
the length from one of the lateral extremities: the summit forms a longitudinal 
ridge, extending with a more or less sinuous convexity along the tooth, transversely 
acuminate, the anterior and posterior surfaces expanding towards the base. From 
the summit the ridge descends rapidly on the one side, ending in a slightly-expanded 
obliquely-obtuse angle : on the other the descent is gentler forming an elongated 
lateral prolongation, triangular in section, and terminating in an acute point. 
Coronal surface, enamelled, punctate, or pustulate, on different specimens ; ridge of 
crown, worn and smooth ; base, large and deep, not well preserved. There is no 
evidence of concentric or other plicee. Examples occur of what appears to be a 
variety of this species. They have a general resemblance in contour and outline, 
broadly expanded near one extremity, the other tapering and elongate, but in place 
of being raised to forma transversely acute cone, the crown is expanded and broad, 
forming a comparatively depressed convex surface, the anterior and posterior margins 
presenting a lenticular outline. Base not exposed. The coronal surface, as in the 
specimens already described, is in some instances covered with small pittings, whilst 
in others, it is raised into small pustulate dots. The large extvemity is either to 
the right or left of the centre, showing in all probability that the teeth have been 
arranged in at least two parallel rows. 
Formation and locality : Mountain Limestone, Armagh, 
Lx coll. Karl of Enniskillen. 
Helodus acutus, Davis. 
(HAL IbIDC, eg, 74)) 
Teeth, small, median cone large, equal in height to the length of the tooth, 
which is ‘4 of an inch. Crown consists of a central cone, with a recurved lateral 
and posterior basal margin. Central cone, obtusely pointed, a slightly angular 
ridge extending from the apex down each side. Anterior surface slightly convex 
transversely, slightly concave longitudinally ; posterior surface transversely rotund, 
expanding towards the base. Basal portion of crown small, extending less than 
half the diameter of the central elevation on each side, concave margin thick and 
recurved upwards. Lateral recurvature extends posteriorly along the margin, 
nearly to the median line, where the margin is depressed. Anterior margin and 
base not exposed. Coronal surface deeply punctate, smooth at the apex. 
Formation and locality: Mountain Limestone, Armagh. Unique specimen. 
Ex coll. Karl of Enniskillen, 
TRANS. ROY. DUB. S0C., N.S., VOL, I. 4B 
