1888.] 



MYRIOPODA, ETC. OF CHRISTMAS ISLAND. 



559 



side to side ; the inferior surface less arched, with its plane meeting 

 the plane of the lateral surface almost at right angles. On the 

 under surface, near the point of junction of the two surfaces, there is 

 a shallow constriction which gives each somite the appearance of 

 being furnished below on each side with a rounded keel-like promi- 

 nence. These prominences form a continuous series extending from 

 the lateral margin of the first tergite to the posterior end of the body, 

 a series which corresponds with the series of inferior keels found in 

 some ( ? all) species of Strongylosoma. 



Foramina repugnatoria small, circular, with slightly raised mar- 

 gins, situated in the middle of the sides of the same somites, as in 

 Strongylosoma, but not supported upon even a trace of a keel ; those 

 in the anterior region of the body situated in the anterior portion of 



Fig. 2. 



Cylindrodesmus hirsufus. 



the posterior half of each somite, those in the posterior region of the 

 body in the posterior portion of the posterior half of each somite. 

 Anal tergite produced behind into a short rounded prominence which 

 slightly overlaps the anal valves ; margins of valves not raised ; 

 subanal plate somewhat quadrate, with slightly concave and con- 

 verging lateral margins, and slightly concave posterior margin, at 

 each end of which is a prominent tooth. 



Legs hairy. Copulatory foot of the male consisting of two 

 segments ; proximal segment, half of which is inside the body, 

 slender and cylindrical above, stout below, and membranous on the 

 inner surface, where it comes into contact with its fellow on the 

 opposite side ; from its distal extremity on the inner surface springs, 

 at right angles to it, the distal segment, which projects forwards 

 parallel to the long axis of the body ; this segment has the form of 

 a slightly waving rod which is sharply upturned towards the distal 



38* 



