No. I.] MORPHOLOGY OF CLADOSELACHE. 93 
rays, stout at the base, whose free tips intercalate to weave a 
stout fin margin. In the posterior fin margin bifurcated tips, 
as we have seen, often interwedge. Compactness of supporting 
elements has the effect of making the fin appear thick and 
immovable, and the inclination of the compressed foremost 
rays tends to give the entire fin the appearance of being 
directed forward. 
As to the attachment of the fins to the body, — basalia 
and shoulder girdle: from the specimens earlier discovered but 
little was to be learned. Newberry asserted the presence of 
basal plates; but of this interpretation of the fossil Smith 
Woodward, as noted above, was skeptical. It was clear that 
the origin of the laterally-placed fin was stout and muscular, 
giving the latter authority, no doubt, an additional reason for his 
conclusions as to the lateral-fold character of the fin. Newly 
obtained specimens, however, showed the present writer that 
basal plates are unquestionably present, and by careful com- 
parison of his material he was enabled to prepare the accom- 
panying figure (Fig. 1) of the shoulder girdle with its 
basalia, which he later found, from Fritsch’s drawings, readily 
comparable with the pelvic structures of Xenacanthus (female) 
There is certainly a series of cartilage plates (basalia) from 
which the rays take their origin. These, however, are broader 
and more of a size than those of Xenacanthus. They lie 
within the body wall, and the distal element does not pro- 
trude. What in the diagram is termed basal (Bas!) may 
not improbably correspond with the element proximal to 
that lettered Bas! in Wiedersheim’s text figure 52; Basalia 
one and two are certainly of great interest as possessing 
coalesced and disappearing fin rays; their arrangement is 
certainly such as might be expected on the principle of fusion 
of proximal elements, and clearly suggests the gradual inturning 
of the anterior end of the line of the basalia. It is further 
instructive in the general principle of fusion that the proximal 
basal elements are smaller and decrease in size as they come 
to be turned towards the median line. Although the present 
material allows a fairly complete idea of the area and position 
of the distal basalia, the separation of the caudad elements 
