U TERRESTRIAL CARBONIFEROUS ARACHNIDA. 



Plesiosiro madeleyi, sp. nov. Plate II, fig. 5; Text-figures 15, 16. 



Integument finely granular. Carapace with its aclnieclian crests finely beaded ; 

 the lateral crests apparently smoother ; three tubercles forming an oblique line in 

 the posterior half of the area on each side between the crests ; the posterior width 

 of the carapace a little less than its median length, the latter a little greater than 

 the length of the anterior five terga of the opisthosoma. Opisthosoma longer than 

 wide, its width about equal to the length of the anterior six terga; a narrow 

 median granular crest on the anterior seven terga, and a few large granules 

 forming an irregular, oblique, abbreviated crest on each side. The eighth tergal 

 plate considerably shorter than the seventh; the ninth and tenth much shorter 

 than the eighth. 



First leg, excluding the coxa, about as long as the body; its femur about as 

 long as the first four terga of the opisthosoma ; and a little longer than the tibia ; 

 the tibia about twice as long as the patella; the basal segment (protarsus) of the 

 terminal tactile portion longer than the other segments individually. Fourth leg 

 with trochanter and femur about equal in length to the carapace. The four 

 distal segments of the palpi about half the length of the carapace. 



Measurements in mm. (of type). — Total length 1 1*5 ; length and width of 

 carapace 5 ; length of opisthosoma nearly 7, its width 5, length of first leg 

 about 11. 



Coseley, near Dudley. 



Type in the Collection of the late Mr. William Madeley. This specimen shows 

 the basal segments of the mandibles, the two palpi, one complete leg of the first pair, 

 the femur, patella, and half the tibia of the third leg, the femur and patella of the 

 fourth, and the femur of the second ; the shape of the carapace and the tergal 

 plates of the opisthosoma. Also the posterior sterna of the opisthosoma ; and the 

 hollow spaces of the basal segments of the legs of the first pair. 



Other specimens in Mr. Madeley's, Dr. Hind's, Mr. Priest's, and Mr. 

 Egginton's Collections show additional features which have made it possible to 

 restore the dorsal surface tolerably completely. Details of the ventral surface are 

 in no instance well preserved, the sterna and the genital area of the opisthosoma 

 being in every case obscurely indicated. A specimen in Mr. Egginton's Collec- 

 tion (No. 4) is noteworthy for being the only one to show ten distinct tergal 

 plates on the dorsal side of the opisthosoma, the ninth and tenth in this specimen 

 appearing as a single plate in the others, where the posterior end of the opistho- 

 soma is preserved (PI. II, fig. 5). 



