however, at stations N12, N21, and N22, where the warm 

 water from Cape Lisburne and Kotzebue Sound is again felt, 

 the larvae again appear, apparently having drifted out with 

 the surface water from areas having a warmer bottom. 



Specific identification of the echinoplutei was not made, 

 but in most samples the larval skeleton was preserved suffi- 

 ciently to indicate the larval type. Examination of numerous 

 specimens revealed only larvae with fenistrated bars in the 

 postoral and postero-dorsal arms and with the body and re- 

 current rods forming a calcareous basket similar to the 

 clypeasteroid, Dendraster excentricus. The basket, however, 

 appeared to be somewhat more open than in the species from 

 Puget Sound, -and the lower ventral transverse rods were not 

 seen. These rods apparently do not always develop until late 

 in the larval life. 



From this survey of echinoplutei found among the plankton, 

 it is evident that either the shallow waters of the Bering Sea 

 and Alaskan coast abound in adults of these animals or the 

 spawning season is especially abrupt and intense during this 

 time of year. 



The ophiopluteus larvae of the brittle stars were more 

 widely distributed, but less abundant than the echinoplutei. 

 Like the latter they were also characteristic of the warmer 

 water (fig. 59). Bipinnarian larvae of sea stars were found 

 only at stations off the Pribilof Islands, Kotzebue Sound and 

 Unimak Island (N2, N3, N21, and N46). It is of special interest 

 to note that the chief plankton constitutent at station N15 was 

 barnacle larvae, mainly in the nauplius stage but including 

 some in the cyprid stage (fig. 60). Other stations in the 

 Chukchi Sea yielded many barnacle larvae. Polychaete worm 

 larvae were scattered throughout the area and were especially 

 abundant at stations N14 and N15 in the Arctic Ocean. Clam 

 larvae occurred throughout the area clear up to the northern- 

 most station, but the greatest concentrations were at station 

 N46 off Unimak Island and at station N7 near St. Lawrence 

 Island. 



Crab larvae were nowhere abundant, but occurred consist- 

 ently at nearly all stations northward to station N15 in the 

 Chukchi Sea. In view of the abundant crabs forming new 

 fisheries in part of the Bering Sea area, it might be expected 

 that pelagic larval stages would be abundant in the plankton, 

 but apparently the season of shedding larvae was past. This 

 observation might be of great economic importance since 

 the fishery operations for these crabs, if made during the 

 summer, would then cause less interference with the re- 

 stocking. 



