348 The American Geologist. December, 1903. 
recess for the reception of the teeth and the lower margin is strongly 
cor rug 
Pectoral fins, large and strong, with from 18 to 23 unjointed rays 
several of which run out on the fore-margrft Between those that de- 
ploy on the hind margin arc secondary intermediate rays and between 
some of these occur even tertiary rays or raylets. The hind margin of 
the fin behind the tips of the rays and about half an inch in width is thin 
and only in some cases shows the presence of trichinosts. 
Owing to the crushed condition of the basal cartilages it is not 
possible at present to make out the details of their arrangement or to 
express a confidenl opinion regarding the type of the fin. No axis such 
as would bespeak an archipterygial tin can be seen. If any such exist 
it lies within the line of the body and is therefore concealed by the 
skin; the fin is entirely uniserial. the fore-rays being stronger at base 
and widening to their tips, the midways being longest, widest in the 
middle and tapering outwardly when the secondaries are intercalated, 
the hind-ray> rapidly diminishing in size and strength as their direction 
changes, till the hindmost are exceedingly weak, thin and -soft. In gen- 
eral outline the fins are broadly triangular and are preserved in their 
fully expanded position, the hind edge being almost at right angles with 
the axis of the body. 
The dorsal fin- are but scantily displayed or not at all in conse- 
quence of the position of the fish, which in almost all cases lies 
belly-upward in the slab. They must have been inferior to the pec- 
torals in strength and solidity, but few details are at present attainable. 
The ventrals are also small and thin rayed : though in somewhat 
better position than the dorsals, they have left but faint impressions of 
their form and size. They were broadly triangular, the basal or long- 
est side being attached to the body. They contained apparently about 
ten rays the largest being medial but all thin and slender. They were 
placed behind the middle of the body. 
The caudal fin is in a few cases partially preserved, but in most 
of the specimens is altogether wanting. The indications are that the 
ventral rays were strong and numerous, but beyond this few details 
can be given. Dr. Bashford Dean, of Columbia College, has figured 
what appears to be a better specimen in which he represents the noto- 
chord turning at almost a right angle with the line of the body and a 
row of cartilages on the dorsal surface filling the angle. If this prove 
correct r.nd general it must be included in the generic definition. 
The teeth while varying in detail are of the well known cladodont 
type, having usually a single median cusp and two lateral denticles 
sometimes half as high as the main point with frequently traces of other 
rudimentary ones beside them. The large cusp is generally slightly 
sigmoid, flat externally, with a slight median concavity in which lies 
•the point of the following tooth and rounded internally with usually 
some slight striation near the base. ::; 
•For the internal structure of the cladodont tooth see the Proc. of the 
Am. Mic. Soc, 1894. 
