PLATE 73. 



Fig. 1. 323. 4. Graptolithus muckonatus. (Pag. 268.) 



1 a. Two fiagments of this species. I b. A portion of one enlarged. 



1 c, (I. Fragments of the same species, one of them much contracted, and both preserving extremely mucro- 



nate teeth. 



Fig. 2. 324. 5. Graptolithus bicornis. (Pag. 268.) 



2 a. A small specimen of the natural size, showing the bifurcation below. 

 2 i. A portion of the same magnified, showing the form of the teeth. 



2 c. A larger specimen having the same character, with a stronger bifurcation, which is thickened at the point 



of separation. 2 d. A portion magnified. 



2 e. A specimen having similar obtuse teeth, with the base removed and the midrib projecting above. 

 2/. A fragment of slate, with several specimens preserving the peculiar radical termination; associated with 



G. ramosus. 

 2 g, h. Magnified portions of these, showing a dissimilar form in the teeth. 



2 i. A fragmeiit in the slate, preserving its original form in a good degree. 2 k. The same enlarged. 



2 I. A fragment in limestone. 2 I'. A more compressed form in the same. 



2m,m'. Enlarged portions of the same. 

 2 m". A magnified view of the edge of a specimen in limestone, showing an appearance analogous to G. sca- 



laris. 2 n. Transverse sections of the same magnified. 



2 o. A slender specimen, with the sides parallel. 

 2 p. A similar specimen, preserving the capillary axis beyond the remaining portion of the stipe. 



2 r, s. Magnified portions of these, showing their identity with the preceding. 



Fig. 3. 325. 6. Graptolithus ramosus. (Pag. 270.) 



3 a, a'. Small specimens near the radical termination, having a simple bifurcation above. 



3 b. A specimen with a more diverging and elongated bifurcation, with a smaller specimen lying obliquely 



across the right ramus. 

 3 ft' & b". The same species. 3 c, d. Enlarged portions of the two last. 



3 e. A specimen with elongated rami, which are serrated on one side only. Fragments of G. Sagittarius on 



the same specimen. 

 3/. A specimen branched below, and bifurcating above. The branches and bifurcate stipe above are serrated 



on one side only ; while the stipe below and between the brandies and bifurcation is serrated on both 



sides. 



3 e, h. Enlarged portions, showing the character of the teeth at the points of divergence, below and upon the 



branches. 



Fiir. 4. 326. 7. Graptolithus scalaris. (Pag. 271.) 



4 a. A specimen showing the radical termination. 4 ft. A portion of the same magnified. 



4 e. A more slender and tapering specimen, with a single range of dissepiments. - 4 rf. Magnified portion. 

 4 e,/. A small fragment, with oblique dissepiments and smooth margin. 



4 g. A specimen with apparently a single range of dissepiments, and a central capillary axis projecting beyond 

 the stipe. 



