TITANOSOMA AND POLYMICRODON IN ENGLAND 149 



obtuse angle against the pre-femur, and the tarsus, which is 

 longer and thinner, is more strongly bent back. For the rest, 

 however, the seventh pair of legs shows no really striking 

 characters; at the most, three somewhat stronger bristles on 

 the inside of the femur may be mentioned. Four or five 

 similar stiff bristles occur in the same position also on the 

 eighth to tenth pairs of legs. The posterior gonopods (IX. 2) 

 are connected by weak transverse muscles with their tracheal 

 pockets. They are placed upon a simple transverse depressed 

 sternite, which presents no special characters in its middle 

 part, but is somewhat expanded at each side in the neigh- 

 bourhood of the stigmatic groove. No considerable move- 

 ment of the hinder gonopods upon their sternite seems to be 

 provided for; the basally expanded coxites are, in fact, 

 attached to the sternite by a broad and three-cornered base. 

 The most anterior of these three corners forms a longitudinal 

 thickening (IX. 2, k), which extends through the basal half of 

 the pre-femur, along the front of the coxite, and ends over the 

 stigmatic groove. Internally the coxite ends in a toothlike 

 projection; otherwise however it possesses none of the dis- 

 tinguishing characters seen in the Orobainosomidas. The 

 longitudinal thickening has an obtuse-angled bend, though 

 without showing any suture between coxa and pre-femur. 

 This suture is completely obliterated in front, while it remains 

 clearly discernible behind. Over it a rounded knob from the 

 pre-femur projects towards the base of the appendage (IX. 

 3, a). For the rest, the two joints are contrasted with one 

 another in that the coxa is naked and distally narrowed, 

 whilst the pre-femur bears bristles and is narrowed proximally. 

 The remaining joints of the appendage are represented by a 

 hook let into the outer side of the end of the pre-femur and 

 directed backwards. 



The anterior gonopods (IX. 4) form a strikingly narrow and 

 compressed appendage upon their much broader sternite, 

 which latter is somewhat trapezoidally expanded towards the 

 base. To give a complete description of these highly com- 

 plicated organs from a single example of the male is scarcely 



