1865.] OF PHYSALUS ANTIQUORUM. 225 
more slender. The thirteenth is compressed from before backwards. 
The fourteenth is thinner and more delicate, though almost as broad 
as the three ribs that go before it ; it is not ridged, but there is a 
slight break in the posterior border of the upper curve (as likewise 
in the thirteenth), which in the next or last rib takes a backward 
arch. 
The fifteenth, like the first and second, has individual peculiari- 
ties. The body of the rib is well developed, and not much shorter 
than the fourteenth and the others in advance. It has a roundish 
head ; and the neck is so twisted that what is the outer surface in the 
ribs before it, here comes to look backwards; and at this part it is 
flattened. There is no angle. The upper third of the body is bent 
in an arched form backwards and slightly outwards; then the rib 
broadens and flattens, while the backward arch is reversed forwards, 
forming in the middle a wide anterior sweep, which, as it approaches 
the free abdominal extremity, curves again backwards, tapering to a 
falciform termination. The rib has thus three grand curves and 
twists, giving it a remarkable, sinuous charactér. 
The accompanying table shows at one view the relative propor- 
tions of the ribs on one side; and in this manner the peculiarities of 
each are well demonstrated. 
Greatest length Greatest : Greatest | Breadth| Breadth | Breadth 
Ribs. following length in | Diameter] breadth of about the of 
outer border | a straight | of chord. of neck. middle free 
of arch, line. head. of rib. point. 
M Stiyim 6 ofa 53 43 10 6 5 44-5 53 
2nd 68 61 16 94 6 41-5 Bt 
3rd 82 72 17 6 yelp DS Ey 
4th 88 78 2 5 44/54 | 32 
5th 90 80 23 4} oF 3-34 32 
6th 91 803 24 32 3 34 3 
7th . 92 81 4 3 3-31 | 8 
8th 89 80 164 | 4 23 | 3-91 | on 
9h ....! 86 77 Lage ae) gee ti gy li 
10th ae 75 4 2% | 8-9) 12 
11th 72 4 24 | 3-2) | 1h 
12th 65 22 2 33-21 14 
13th . ; 63 eS . } Beet | ie 
14th . 63 =. AE 
15th 633 de Urtpp vg 1% 
The sternum is a strong solid bone; somewhat cruciform, widest 
transversely, with concave borders. The anterior projection is broadly 
rounded ; the lateral projections are flatly conical ; the posterior is 
somewhat similar, but narrower, circular, and taper-pointed. In 
front the central surface is slightly hollowed, the anterior and poste- 
rior processes are moderately bent forwards ; So that on looking on 
the sternum sideways it has a concave appearance in front, with the 
lateral expansions thrown backwards. Its greatest length is 17!, 
and breadth 22". Across the base of the anterior projection there 
is a breadth of 9", of the lateral processes 52", and of the posterior 
Proc. Zoou. Soc.—1865, No. XV. 
