1870. ] HANCOCK AND HOWSE—LEPIDOTOSAURUS. 559 
have been about thirty ribs. In front, too, there are indistinct im- 
pressions of one or two more; but whether or not these terminate 
the series in this direction, it is impossible to say. 
The largest ribs, which are near the centre, are 6} inches in 
length, following the curve, and the shaft is one quarter of an inch 
thick; they taper slightly towards the distal extremity, and do not 
exhibit the longitudinal groove or depression usually observed in the 
ribs of Labyrinthodonts, neither are they apparently depressed in 
the usual manner. The proximal extremities are crushed and 
broken, but are widened a little, indicating a double articular sur- 
face; these extremities are, however, too imperfect to warrant any 
confident assertion of the fact. 
The greater number of the ribs have a crystalline appearance, as 
if composed of a dark grey carbonate of lime; but the concentric 
bone-layers are for the most part conspicuously displayed. Eleven . 
or twelve of the anterior ribs have more than an inch of their distal 
extremity broken away, and the ruptured ends are united to an 
irregular, narrow, thin, longitudinal belt of bone (f), which is in the 
same crystalline condition as the ribs, and which has a fanciful re- 
semblance to a fragmentary breast-bone; but this appearance is 
altogether illusory, for, though this long belt is completely incorpo- 
rated with the extremities of the ribs, the result merely of pressure, 
it is undoubtedly composed of the remains of a few of the dermal 
scales to be afterwards described. 
The limbs are not present, nor can any trace of them be observed. 
There is, however, a thickish mass of bony matter in the dorsal region 
in front (9, g), lying incorporated with the proximal extremities of 
eight or nine of the anterior ribs, and extending in advance of them 
nearly as far as the curved line of the cervical vertebrae. This may, 
perhaps, be the remains of the scapule and other members of the 
shoulder-girdle ; but the forms of the parts are entirely obliterated ; 
indeed there is no indication of the mass having been composed of 
distinct parts. The thickness of the bone, which, however, cannot 
be easily accounted for in any other way, justifies the above suppo- 
sition ; and in fact, from its extent, measuring as it does 5 inches 
long and nearly 2 inches wide, the fair inference would seem to be 
that the fore limbs must have been largely developed. 
There is, however, another explanation which has been suggested, 
which, though possible, can scarcely be considered probable: it is 
that this bony mass may be the remains of the large pectoral plates 
found in all Labyrinthodonts, which in some way or other have been 
removed thus far from their natural position. But this bony mass 
lies united to the ribs, and is covered by the dermal scales already 
alluded to, which appear to be undisturbed. This could scarcely be 
the case did this bony mass originate in the transported pectoral 
plates. 
Further back, incorporated with the dorsal extremities of the ribs 
there situated, is another considerable accumulation of bony mat- 
ter (h) in the form of a very irregular elongated belt. The greater 
portion of this is undoubtedly derived from the surface-scales and 
