82 Dr. R. H. Traquair—Carboniferous Selachii. 
Ctenacanthus costellatus,’ I was inclined to believe that Ctenacanthus 
and Cladodus represented the spines and teeth of the same genus, 
and that the genus itself was Hybodont. 
Mr. Garman, however, in his paper on Chlamydoselachus disputes 
that view, and claims that remarkable recent shark which has only 
one dorsal fin and no spines at all—a form placed by Dr. Giinther 
in the family Notidanida—to be the modern representative of the 
ancient Cladodonts. It is perfectly true that the small teeth towards 
the angles of the mouth in Chlamydoselachus when seen from the 
front strongly resemble those of Cladodus, yet this resemblance is 
not very apparent in those which cover the greater part of the jaws, 
while the bases of the teeth are to my eye strikingly dissimilar. I 
cannot therefore, without further evidence, accept Mr. Garman’s very 
confident assertion that Chlamydoselachus is a Cladodont, leading as it 
does to the inference that Cladodus had no dorsal spines. That Cladodus 
at all events is not quite so close to Chlamydoselachus as Mr. Garman 
believes is, I think, fully shown by a remarkable specimen from the 
Carboniferous Limestone of East Kilbride, Lanarkshire, which has 
been lent to me for description by its possessor, Mr. James Neilson, 
of Glasgow.? This specimen was recovered from the quarry in 
separate pieces by the late Mr. A. Patton, who, I understand, did not 
feel sure that they all belonged to the same specimen. However, 
the fragments were pieced together by Mr. Neilson, and after a most 
careful scrutiny of the whole, I have come to the conclusion that 
the fragments do belong to the same specimen and are rightly 
arranged. We have first a head, compressed from above downwards, 
whose jaws are crowded with truly cladodont teeth of the type of 
C. mirabilis, though apparently belonging to a hitherto undescribed 
species. This is followed by a mass of crushed and inextricably 
confused cartilages representing the branchial apparatus, and 
then come two scapulo-coracoids, each with a pectoral fin attached. 
The fin of the right side is the better preserved, and shows first a 
number of elongated radial pieces whose bases, separated from the 
rest by joints, are attached directly to the shoulder-girdle and 
evidently represent the propterygium and metapterygium of ordinary 
Selachii. Behind these is an oblong metapterygium bearing radials 
preaxially, whose anterior portion seems to have absorbed the bases 
of one or two adjacent radials, but whose posterior extremity is con- 
tinued backwards as a long narrow segmented stem consisting of 
nine rectangular joints, and reminding one at first sight of a vertebral 
column! This part in both fins is cut off by the edge of the stone, 
so that its actual length and number of segments are not seen. Some 
small radials are seen attached to the preaxial side of the first two 
segments,—none on the others, or on the postaxial side of the stem. 
The interest of this specimen is extreme, as it is at least capable 
of bearing the interpretation that we have here a veritable uniserial 
1 Grou. Maa. Jan. 1884, pp. 3-8. 
2 As I have promised to ‘lay a detailed description of this specimen before the 
Geological Society of Glasgow, I can only make a few general remarks upon it in 
the present instance. 
