52 



Alexander Petninkevitch . 



femur is more slender and considerably longer than the patella. 

 The hand is as wide as the patella, the immovable finger compara- 

 tively short and almost straight. The median eyes are small, oval, 

 about V4 the length of the cephalothorax distant from the anterior 

 edge. Side eyes not present or at any rate not preserved. The 

 abdominal tergites increase in length from the first to the seventh 

 which is the longest. The second to sixth tergites have each a 

 median crest and the fifth and sixth have besides two short, curved 

 grooves, diverging posteriori}'. The post- 

 <^ abdomen lies on its side and each segment 



shows two deep grooves which correspond to 

 what have been in life the lateral crests. 

 The seventh post-abdominal segment is 

 slightly longer than the cephalothorax and 

 2\'.2 times sa long as high. The poison gland 

 is small with a curved sting and without 

 a spine. 



Specimen No. 132, Plate III, fig. 15, is con- 

 siderably larger, but resembles in all details 

 the type specimen. Although the nodule 

 containing this specimen shows both the ob- 

 verse and reverse, yet the ventral surface is so 

 badly deformed, that no details of structure 

 can be made out. Total length 21.2 nmi. 

 Cephalothorax 3.0 mm. long. Its correct 

 width cannot be ascertained owing to the 

 fact that the specimen is considerably com- 

 pressed longitudinally. Two oval eyes about 

 Vs the length of the cephalothorax distant 

 from the anterior edge. Abdomeny. 3mm. long, post-abdomenii. 5mm. 

 (not including the poison gland). Seventh post-abdominal segment 

 as long as the cephalothorax and 2^/0 times longer than high. Right 

 pedipalp 12.5 mm. long, the hand somewhat slenderer than in 

 the type specimen. The fourth left coxa, the only one visible, is 

 abutting against the sternum, but the shape of the latter cannot be 

 ascertained. The genital opercula are in the form of a transverse 

 figure 00. 



Found in the Pennsylvanic (Lower Allegheny) of Mazon Creek, 

 Illinois. 



Fig. 15- 



Figure 15. — Eoc/omms 



miniitus n. sp., holo- 



type, Peabody Mus. 



No. 131. X Y 



