136 BULLETIN OP THE BUREAU OF FISHERIES. 



The Canadian list of Whiteaves records about the same number of isopods (26) as 

 have been listed for Woods Hole. Of these, nearly half (12) are common to the two 

 lists. A somewhat greater number (30) is comprised in the Plymouth list, of which 

 only 5 appear to be common to our local fauna. Twenty-four species have been 

 recorded by Herdman for the Irish Sea, while Graeffe lists 51 species, some of which, 

 however, are terrestrial. 



The representation of this order in our dredgings is very slight. The figure repre- 

 senting the average number of species per dredge haul is only 0.4, while not a single 

 species was taken with sufficient frequency to occur at one-fourth or more of the sta- 

 tions. The species having the widest occurrence was Idothea pkosphorea, which was 

 taken at 72 of the regular stations. 



Only four species of this order were dredged by us with any frequency, and one 

 of these (Idothea baltica) probably finds its more proper habitat among rockweed and 

 eelgrass, whether growing alongshore or floating at the surface. It is thus possible 

 that all of the specimens which were dredged by us actually came from floating material 

 of this sort.* 1 



One of the other species, Leptochelia savignyi was only taken at 11 stations, and 

 these were all inshore stations of the Phalarope series. The species is abundant among 

 floating weed, upon piles, etc., and probably does not belong to our deeper water fauna. 



The two remaining species (Idothea phosphorea and Erichsonella filiformis) appear 

 with considerable frequency in our dredging records. Of these the latter appears to be 

 of pretty general distribution, occurring with nearly the same relative frequency in the 

 Bay and the Sound, while the former is in a large degree restricted to the Sound, appear- 

 ing in the Bay records only from stations near the lower end, in the vicinity of land. 6 



Isopods dredged by the Survey. 



*Leptochelia savignyi (chart 103). 



Cirolana concharum. 



Chiridotea caeca. 



Idothea metallica. 

 "Idothea baltica (chart 104). 



*Idothea phosphorea (chart 105). 



Edotea acuta. 



Edotea montosa. 

 *Erichsonella filiformis (chart 106). 



Stegophryxus hyptius. 



Of the four commoner species, one (Idothea phosphorea) may be regarded as pre- 

 dominantly northern, having a range upon our coast which is stated by Miss Richardson 

 as "coast of New England to Halifax, Nova Scotia, and the Gulf of St. Lawrence." 



Two of the species may be regarded as predominantly southern, as follows: 



Leptochelia savignyi Provincetown , Mass., to southern New Jersey (England to Senegal). 



Erichsonella filiformis Nantucket Sound to Florida and the Bahamas. 



One of the species (Idothea baltica) may be regarded as cosmopolitan, having been 

 recorded from points as widely removed as Java and the Baltic Sea. On our coast it 

 is said to range "from Nova Scotia and Gulf of St. Lawrence to North Carolina." 



a- Miss Richardson gives the bathymetric range of this species as "surface to 119 fathoms." 

 6 Our 1909 dredgings confirm these statements as to both ! 



