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PROCEEDINGS OF THE NATIONAL MUSEUM 



hauls were 100-0 m. except where the depth of the water was less 

 than 100 m. In 1953 hauls were made from the bottom (usually less 

 than 100 m.) to the surface. 



In both 1950 and 1951 P. abyssorum occurred at about half the sta- 

 tions occupied and in about the same numbers. The average number 

 per station (adjusted to 100 m. vertical tow) was 2.3 in 1950 and 2.6 

 in 1951 . Distribution in the Beaufort Sea appeared not to be associated 

 with variations in temperature or salinity. 



P. abyssorum was somewhat less numerous in the 1953 Burton Island 

 samples, and was captured at only 4 of the 25 stations in the Prince of 



Figure 12. — Paratheviisto abyssorum Boeck, distribution in the Chukchi and Beaufort 

 Seas, U.S.S. Burton Island 1950 and 1951 cruises combined. Solid circles, positive 

 stations; open circles, negative stations. 



Wales Strait. The average number per station was 0.75; the average 

 number per positive station, 1.50. 



All the specimens of P. abyssorum collected on the Burton Island 

 cruises were juvenile, with the exception of one ovigerous female, 

 14 mm. in length, taken at station 3, off Cape Parry, hi a tow from 

 420 m. to the surface, August 8, 1953. 



Little is known about the life history of P. abyssorum. Bogorov 

 (1940) studied the life cycle in the Barents Sea and concluded that 

 spawning occurs in "the second half of the winter season (about Febru- 

 ary)." He further concluded that the individual requires 2 years 

 to grow to maturity, breeds once, and dies. The breeding season 

 appears to be more prolonged than indicated by Bogorov, since at 

 least some breeding occurs in the Beaufort Sea in August (see above), 

 and Stephensen (1933) reported ovigerous females taken June 12 and 



