1888.] 



NATURAL SCIEiJCES OF PHILADELPHIA. 



201 



1 m. ; width of abdomen at the base 3-5 mm.; width of abdomen at 

 the apex 1-75 ; width of the eephalothorax at the caput 2-25 ; width 

 •of cephalothorax from margin to margin across the middle 3-5 mm. ; 

 length of palps 2 mm. Both palps are represented by rather thin 

 lines, showing slight marks of joints, and on one palp is a suggestion 

 of a terminal bi!lb which might indicate it to be a young male. 



The caput and median part of the cephalothorax as viewed from 

 the cast, are well elevated and defined ; the cephalothorax narrows 

 towards the abdomen. But in the original imjjression in the rock 



Fig. 2. Eoaiypus Wood- 

 wardii x 4 Outline side view 

 of body. 



I K. 1 i o , ^ ■.run, X 1 



and less distinctly on the casts, there ai:)pear outlines on either side 

 of the margin of the cephalothorax, as though by pressure those 

 parts had been flattened, and only the caput and a part of the dor- 

 sum of the cephalothorax along the median line had withstood the 

 pressure and had been pushed upward into the matrix by the same. 

 These outlines are visible, but not as distinct in the plaster cast. 

 It is at this point that one experiences difficulty in determining 

 •whether the specimen is related to Attus or Atypus. If the broader 

 marginal markings are impressions of the original cephalothorax, 

 the inference would be that the spider represented by this fossil be- 

 longed to the Atypinae. That such is the case, I am strongly in- 

 clined to believe, both on the ground just named, and the charac- 

 teristics of the mandibles, as well as the general facies of the impres- 

 sion and cast. (See Fig. 1.*) In the absence of the characteristic 

 eyes and long, jointed superior spinners it would be impossible to 

 relegate the specimen to the genus Atypus with absolute authority. 



* This figure has been drawn from the cast and compared carefully with one 

 kindly made for me in the Geological Department of the British Museum, and fur- 

 nished by the Keeper, Dr. Woodward, 



14 



