414 



narrow and the long somite VII is the narrowest, forming a "wasp waist" 

 so characteristic of the external appearance of the species of Phron- 

 ima. The border of the coxal plates is discernible with difficulty only 

 on somites III-V. The 5th segment of pereopods V is broadened and 

 strongly chitinized, and together with the 6th segment forms a power- 

 fully developed subchela; thus the crustacean resembles a scrawny boxer 

 sporting oversized boxing gloves. The structure of the subchela of the 

 adult crustacean is important in determining the species affinity; here 

 special attention is paid to the structures of the distal margin of the 5th 

 segment, which in various species may be highly developed or absent; 

 the anterior distal angle is generally extended in the form of a tooth 

 (anterior distal tooth); the distal margin is raised in the middle as a 

 tubercle with its apex often furcate, the anterior projection is generally 

 pointed (medial denticle of the distal margin), the posterior projection 

 (medial protuberance of the distal margin) is usually rounded and often 

 with additional tubercles on the posterior margin. The posterior margin 

 of the 5th segment is more or less bulged, sometimes with a project- 

 ing posterior proximal angle. The uropods have virgate basipodites and 

 lanceolate rami. Uropods II are well developed in both sexes but are 

 shorter than the rest. 



This genus, as accepted by us, includes eight species. 



Type species: Cancer sedentarius Forsk&l, 1775. 



337 KEY TO SPECIES OF GENUS PHRONIMA 



1 . Pereon somite VII shorter than pleon somite I . 



4. P. stebbingi Voss. 



— Pereon somite VII longer than or equal to pleon somite I 2. 



2. Endopodite of uropods II at least half length of exopodite. Sec- 

 ond segment of pereopods V S-shaped (in females more so than in 

 males) 5. P. curvipes Voss. 



^- Endopodite of uropods II more than half length of exopodite or 

 roughly equal in length. Second segment of pereopods V straight . . 

 3. 



3. Length of 5th segment of pereopods V of female much more than its 

 width; anterior distal tooth almost of same length as segment itself 

 or slightly shorter; medial protuberance of distal margin of segment 

 high and triangular, medial denticle absent. Male with reduced anten- 

 nae II \. P. sedentaria (Forsk&l). 



— Length of 5th segment of pereopods V of female slightly more than 

 its width or equal to it; length of anterior distal tooth less than half 

 lenght of segment; structures of distal margin different. Male with 

 well-developed antennae 4. 



