FISHERY BULLETIN: VOL. 83, NO. 3 



In all described stages, carapace and abdominal 

 somites not flared laterally; antennal scale relatively 

 long and narrow (about 5-7 times as long as wide). In 

 Stages I-III, but rarely in Stage IV, carapace with 

 denticles along anteroventral and posteroventral 

 margins; posterior margin of abdominal somites 1-5 

 fringed with spinules (Fig. 7). Rostrum sinuate, pro- 

 jects somewhat upwards in Stages I-III, remains 

 shorter than carapace as late as Stage VIII, without 

 teeth until Stage IV. Antennal flagellum shorter 

 than antennal scale through at least Stage V. 

 Length: Stages I- VII, 3.1-13.0 mm. Range: Bering 

 Sea to San Nicolas Island, CA; depth, 5-1,984 m 

 (Butler 1980). 



Key XII.— Larval stages (Stages I-VII) of Pandalus 



tridens. 



1. Eyes sessile; carapace without supraorbital 

 spine; pereopods 1-3 without exopodites; 



telson with 7-1-7 setae Stage I 



Eyes stalked; carapace with supraorbital 

 spine; exopodites on pereopods 1-3; telson 

 with 8-1-8 setae 2 



2. Uropods enclosed Stage II 



Uropods free 3 



3. Endopodite of uropod < 1/2 length of 



exopodite Stage III 



Endopodite of uropod > 1/2 length of 

 exopodite 4 



4. Rostrum with 2 dorsal teeth; endopodite of 

 uropod about 3/4 length of exopodite; telson 



widens posteriorly Stage IV 



Rostrum with > 2 dorsal teeth; endopodite of 

 uropod nearly same length as exopodite; 

 lateral margins of telson nearly parallel 5 



5. Antennal flagellum with 5 segments and 

 about 2/3 length of antennal scale; chela of 

 pereopod 2 slightly developed (Fig. 8); pleo- 

 pod 2 about 1/4 height of abdominal somite 



2 Stage V 



Antennal flagellum with ^ 20 segments and 

 as long as or longer than antennal scale; 

 chela of pereopod 2 well formed (Fig. 9); 

 pleopods 2 at least 1/2 height of abdominal 

 somite 2 6 



6. Rostrum with 6 dorsal teeth; pleopods 

 without setae; telson slightly wider near 

 center Stage VI 



Figure 7. -Abdomen, Stage II zoea 

 of Pandalus tridens showing spinules 

 on posterior margins of somites. 



0.25 mm 



Figure 8. -Chela of pereopod 2, Stage V zoea of 

 Pandalus tridens. 



274 



