Palaeozoic Arachnida of North Aiuerica. 67 



Total length without pedipalps i6 mm. Cephalothorax 4.1 mm. 

 long, 5.8 mm. wide in the widest place, wdth a median depression as 

 in text figure 28. Abdomen 9.6 mm. long; it consists of eleven seg- 

 ments and a short pygidium. The pleura is clearly segmented. The 

 pedipalpi are heavy and long. The first pair of legs is not preserved, 

 but presumably it was thin and long. The second femur is 5 mm. 

 long, the third 7 mm. The fourth leg is much thinner than the third, 

 its femur is 5.6 mm. long, and the total length of this leg from the 

 base of the trochanter to the end of the last visible joint is 21 mm. 

 Whether the transverse lines represent the limits of joints it is not 

 possible to ascertain. The whole body is smooth. 



The -general appearance of this specimen reminds one much of 

 a true whip scorpion, but the shape of the cephalothorax is character- 

 istic of the sub-order Amblypygi and there are no signs of a whip, 

 although the abdomen is in an excellent state of preservation. 



From the Pennsylvanic (Lower Allegheny) of Mazon Creek, Illinois. 



Genus Graeophonus Scudder 1890. 

 New definition. Cephalothorax wider than long, reniform, with 

 one pair of eyes placed on an e^-e tubercle. Third and fourth pair of 

 coxae triangular, meeting in a median point. Trochanters two- 

 jointed. Abdominal tergites ten. Genotype G. carhonarius Scudder. 



Graeophonus carhonarius (Scudder). 

 Plate V, figs. 27—29 ; text figs. 29—31. 



= Lihelliila carbonaria Scudder, Can. Nat., (2), Vol. VIII, 1876, 

 p. 88, fig. I. 



G. carhonarius Id., Mem. Boston Soc. Nat. Hist., Vol. IV, 1890, 

 p. 454, pi. 40, figs. 2, 3, 6. 



Scudder drew the characters of this species from specimen No. 1762 

 of the Lacoe collection " before it was recognized as the same species 

 as that described by many years ago from an abdomen alone, under 

 the name of Lihellida carbonaria." Since both specimens received the 

 same specific name and since the generic characters were first drawn 

 by Scudder from specimen No. 1762, moreover since this specimen is 

 the more complete one, it should have the value of the holotype. 

 We must remember that characters of extinct arachnids do not have 

 the same value as those of recent forms. It is probable that Libellula 

 carbonaria belongs to the same genus and species as Graeophonus 

 carhonarius, but the specimen is too incomplete to make it an ab- 

 solute certainty. I have carefully compared the type specimen of 

 Libellula carbonaria with the type specimen of Graeophonus carhonarius 



