100 



Order UROPYGI. 



At once recognizable from the Scorpions, to which the larger 

 species present considerable superficial resemblance, by the presence 

 of a deep constriction between the cephalothorax and abdomen, 

 by the absence of pectines or combs on the sternal area and of 

 poison-glands in the postanal skeletal piece. 



Cephalothorax longer than wide, the carapace sometimes seg- 

 mented posteriorly : the ventral surface narrow and furnished with 

 two or three sternal plates (fig. 31, p. 103) an anterior or pro- 

 sternum, broad in front and narrowed behind, lying behind the coxae 

 of the chelae and separating the bases of the anterior legs ; a pos- 

 terior or metasternum which lies between the coxae of the 4th pair of 

 legs ; and sometimes a minute mesosternum between the coxae of the 

 3rd legs. Mandibles chelate, consisting of two segments. Chelce 

 large and prehensile ; the segments named as follows from base 

 to tip : coxa, trochanter, femur, tibia, hand, finger ; the coxae united 

 in the middle line and furnished in front with a pointed maxillary 

 process. Legs of 1st pair long, slender, and antenniform, consisting 

 of six segments : coxa, trochanter, femur, patella, tibia, and tarsus ; 

 the tarsus subdivided into 8 or 9 segments, the basal of which 

 is very short. The rest of the legs ambulatory in function, and 

 consisting of 7 segments named as above with the addition of a 

 protars-us which precedes the three-jointed tarsus; the tarsus 

 bearing three claws ; coxae of 2nd and 3rd legs not widely separated 

 in the middle line of the sternal area. Abdomen consisting of 12 

 somites, represented by tergal and sternal plates, but the sternum 

 of the 1st wholly or partially obliterated, at most forming a 

 strengthening skeletal piece on the underside of the waist, 

 and in systematic descriptions not taken into account, the sternum 

 of the 2nd somite being termed the 1st abdominal sternum. 

 Generative organs opening in the middle line behind the sternum of 

 the 2nd somite, which is often much modified. Last three somites 

 annuliform or cylindrical, forming a movable stalk for the post- 

 anal skeletal piece, which consists of a single segment or has the 

 form of a many-jointed caudal flagellum or filament. The un- 

 modified terga and sterna impressed with a pair of muscular scars 

 or sigilla. 



The two suborders into which the genera of this Order are 

 classified may be briefly diagnosed as follows : 



a. Carapace unsegmented ; last segment of ab- 



domen bearing a long jointed flagellum .... UBOTRICHA. 



b. Carapace segmented : last segment of abdomen 



bearing a short unjointed skeletal piece .... TABTAEIDES. 



