FISHERY' BULLETIN; VOL. 69, NO. 4 



sampled water layers adjacent to the sea bed 

 (sled net). These results suggest M. bigeloivi 

 lives in or on the bottom sediments during much 

 of its life. 



An analysis of the types of bottom sediments 

 at the collecting sites reveals a high incidence 

 of this mysid on various grades of sand (Table 

 6), usually sand containing little or no silt or 

 clay. They tend to avoid fine-grained sediments 

 as further evidenced by their absence in several 

 hundred samples taken from a 1,000 square km 

 area of predominantly silt and sandy-silt sedi- 

 ments south of Martha's Vineyard, Mass., on 

 research vessel Delaircrre cruise 62-7. 



Table 6. — Frequency of occurrence of Mysidopsis bigel- 

 owi in various t>-pes of bottom sediments, based on the 

 NMFS collection. 



Bottom type 



Samples 



Specimens 



Relation to Water Temperature 



M. bigeloivi inhabits water temperatures from 

 about 2° C in the northern part of its range to 

 summer water temperatures of about 30° C in 

 the Florida and Louisiana areas. The annual 

 change in temperature is slightly less than 20° C 

 in the north and slightly more than 20° C in the 

 south. 



Mysidopsis ftirca Bowman, 1957 



This species was de.scribed by Bowman (1957) 

 from a sample containing 23 specimens collected 

 in 1953 by the research vessel Theodore N. Gill. 

 The specimens were obtained at one station 

 (number 57) located 40 km from shore off the 

 northern coa.st of South Carolina. Depth of 

 water at the collecting site is 22 m. It was later 

 reported by Brattegard (19(59) from off south- 

 eastern Florida at depths of 1 to 48 m. 



The NMFS collection contains one specimen, 

 a female 4.2 mm long, taken with the Campbell 



FiGiRE 12. — Geographic distribution of Mysidopsis furca 

 based on a specimen in the collection at the NMFS Bio- 

 logical Laboratory, Woods Hole. 



grab 50 km east of Georgetown, S.C, (Figure 

 12; Burns and Wigley, Table 13) about 50 km 

 southwest of the type locality. The specimen 

 was taken at a depth of 22 m on sediment com- 

 posed of fine sand. This small species has a 

 reported size range of 4.6 to 6.1 mm (Bowman, 

 1957). Neither the size nor the develojimental 

 stage of the NMFS specimen provides any indi- 

 cation of sjiawning season or size at maturity. 



Promysis atlantica Tattersall, 1923 



This rare species was described from an im- 

 mature female specimen collected off Rio de Ja- 

 neiro, Brazil, in 1910 (Tattersall. 1923). It 

 was not reported again until Clarke (1956) de- 

 scribed the male and adult female, and gave 

 new records of occurrence for specimens col- 



732 



