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PLATE XIII. [PLate 24.] 
SECTION 2.—PTERYGOTUS. 
1. Plerygotus acuménatus. An endognath with part of its palpus. 
. 2. An endognath with palpi, from the same slab as the segments of the body figured in 
Plate IL. Fig. 11. 
. 2a. The opposite impression of the same specimen. 
- 3. Another specimen, with one (or two) endognaths and the proximal divisions of their 
palpi, covered by part of the ectognath y, «, (described p. 223). 
. 4. A branched palpus, or a pair of palpi (see pp. 187, 223.) 
The above are from Upper Ludlow Rock, Lesmahago. 
. 5. Pterygotus punctatus. Hinder segment of the body? U. L. Ludlow. 
- $a. The plicze magnified. 
. 6. One of the proximal joints of an antenna. 6a. The sculpture magnified. From 
the same locality. 
7. A portion of a very young antenna. From the same locality. 
. 8. Pterygotus arcuatus. Part of one ramus of the chela of an antenna, similar to that 
represented in Plate XII. Fig. 9. U. L. Ludlow. (Mr. J. Harley’s cabinet.) 
9. Pterygotus punctatus. A large and perfect endognathary palpus. (Mr. H. Salwey’s 
collection. ) 
10. A portion of one of its curved processes magnified. 
11. P. punctatus. One joint of a very large endognathary palpus, showing the two 
curved processes. U. L. Ludlow. (Cabinet of Mr. Lightbody.) 
12. P. arcuatus. A large segment of the body (the second). 12a. The sculpture mag- 
nified. Lower Ludlow, Leintwardine. 
13. A transverse section of a segment of the body. From the same locality. 
14. P. punctatus. Part of the basal joint of an ectognath. From the same locality. 
15. P. arcuatus? Part of anendognath. 15a. Its sculpture magnified. 
16. An abdominal? or thoracic ? appendage of the same species, showing the incised un- 
equal lobes of the penultimate joint ¢, ¢, and the terminal palette a, 6. 
17. This figure represents the fossil whose nature is discussed at p. 190. (Mr. H. 
Salwey’s collection.) Lower Ludlow, Leintwardine. 
In the Museum of Practical Geology, unless it be otherwise stated. 
