22 GEOLOGICAL MEMOIRS. 



enkernen). The anterior rays are very short and thin, the succeeding 

 ones increase in length and thickness. Immediately before the knee- 

 shaped angle there arises a carpal ray, distinctly articulated, turned 

 backwards, and 3 inches 8 lines long. On its outer side it has seven- 

 teen thick, strong rays, much divided externally, and, as a remarkable 

 peculiarity, also on the inner side a smaller number of weaker rays 

 divided in a similar manner towards their point. 



The pectoral fins had consequently a great extent and an anomalous 

 {ahweichende) structure. 



The pelvic arch is less distinctly preserved. A broad, short bone 

 proceeds obliquely forwards from the spinal column, and attached to 

 it is the knee-shaped tarsal ray turned backwards, which with its 

 numerous fin-rays, attached on the exterior side, and likewise much 

 divided towards the point, forms a large fin. Whether the bundle 

 of fibres (seen in the figure) extending from the vertebral column to 

 the knee-shaped angle indicates a bone, and whether this belongs to 

 the right or left ventral fin, cannot be ascertained. Remains of the 

 former, however, are apparently indicated between the vertebral 

 column and the carpal ray. 



Close behind the pelvis, opposite the ventral fin, are situated the 

 remains of a dorsal fin composed of numerous rays. The body being 

 broken off at this point, it is uncertain whether there was also a 

 second dorsal fin. 



It is thus evident that this skeleton belongs to a cartilaginous fish, 

 with a semi-ossified vertebral column, of the order of Selachii, — a fish 

 which from the breadth of its head and pectoral fins, and the small 

 thickness of its body, resembled the living genus Squatina. But as 

 it is probable that the opening of the mouth corresponded to the 

 circumference of the head, and as the carpal ray of the pectoral fin 

 is furnished with fin-rays on its inner side also ; its alliances can 

 only be sought for among extinct genera, of which, so far from any 

 completely preserved skeleton having as yet been found, in general 

 the teeth and the cervical spine form the only basis of comparison. 

 The numerous fragments of small teeth, lying along the right-hand 

 margin of the head, render it probable that there were several 

 rows of them. The anterior teeth are larger than those placed 

 farther back, so that the form of some of them can still be recog- 

 nized*. When magnified, it is seen that from each root three conical 

 points arise, a large one in the middle, with a smaller one on each 

 side. They are slightly compressed from within outwards, so that 

 the interior side appears flatly convex, the outer side almost flat. 

 Both sides are longitudinally furrowed and covered with a shining 

 enamel. In fig. 10 «f, several broken teeth lie above each other, of 

 which the one in front seems to have four points ; in fig. b the inner 

 convexity is shown ; in fig. c the more flat external side. Similar 

 teeth characterise the genus Hybodus (Agass. I.e. p. 178. tab. 22. 

 a. 24), but its cervical spine is very difl'erent from that of the present 



* See fig. 10 of original. 



t Tab. 5 of the original Memoir, 



