503 



Length of females up to 30.5 mm, of males up to 27 mm. 



Dimorphism is observed among females due to earlier or later sexual 

 maturity. A smaller form (10-15 mm) exists, which has been described 

 by Streets (1878) as O. bulbosus, and the large "typical" form described 

 by Claus as O. similis (Claus, 1879b), in which the females mature at a 

 body length of more than 20 mm (Fage, 1960). The smaller form differs 

 in the almost spherical head, the dorsal part of which projects strongly; 

 the head tapers sharply toward the rostrum; its maximum height is 2/3 

 the length with rostrum. In the larger form the head is developed more 

 407 proportionately, smoothly extends into the rostrum, and is almost not 

 projected dorsally. The length of the head with rostrum is more than 

 twice its maximum height. Males do not differ in body shape and are 

 closer to f. ty picas, although sexual maturity may set in at greatly varying 

 sizes. The rostrum constitutes half the total length of the head. 



The 2nd segment of pereopods I is longer than the rest of the leg, 

 has parallel margins, and is twice longer than wide; the 5th segment 

 is almost squarish and has weakly bulged margins; the distal margin is 

 anteriorly rounded, posteriorly extended and pointed, and the inner part 

 of the process is coarsely denticulate; the entire posterior margin up to 

 the tip of the process and the analogous margin of the 4th segment are 

 finely denticulate and bear isolated setae; the 6th segment has a bulged 

 posterior and straight denticulate anterior margin; fine dense setae occur 

 on the posterior surface and a few setae in the distal part of the anterior 

 margin; the process of the 5th segment is basally covered with fine 

 dense setae. Pereopods II are longer than pair I; the 2nd segment is the 

 same width as in pereopods I and the ratio of length to width is 4:1; 

 the 5th segment has almost parallel margins, is somewhat longer than 

 wide, and the anterior margin is not stretched distally; the process of 

 the chela is longer than half length of the segment and reaches the base 

 of the claw; the 6th segment bears a few strong short marginal setae; 

 the 5th segment bears similar setae on the posterior margin as does the 

 inner side of the process; the chela has strong blunt-tipped denticles on 

 the inner side. In pereopods III-IV the posterior margin is armed with 

 sparse setae, the anterior margin smooth, and setae occur only in the 

 distal part of the 4th-6th segments. In pereopods V the 2nd segment is 

 ovally broadened, 1 .5 times longer than wide, equal to the total length of 

 the 3rd-5th segments, with the maximum width in the middle part of the 

 segment; the 4th segment is equal to the 6th in length, the 5th shorter. The 

 anterior margin of the 2nd segment has low sparse denticles and setae; 

 the ornamentation of the 4th-6th segments is similar in pereopods IV. 

 The 2nd segment of pereopods VI is strongly broadened, the posterior 

 margin roundly bulged, especially proximally, its width almost equal to 

 its length, the posterior margia smooth, and the distal half of the anterior 



