CRUSTACEA MALACO6TRACA. III. ,87 



M. S.ihin lias thus been taken in depths from 4 to 197 fath.; according to Stuxberg the tem- 

 perature at Uie bottom was generally between -*- 0-4 and -r- 17, while small specimens have been found 

 in so high a temperature as 2-6. 



127. Mesidothea megalura G. O. Sars. 



1879, Chiridothca megalura G. O. Sars, Arch. Math, og Naturv. Vol. IX, p. 432. 

 ! 1885. Glyfitonohu megalurus G. O. Sars, North-Atl. Exp. Crust. I, p. na; PI. 10, figs. 1-23. 

 1901. Chiridothfa megalura Ohlin, Bill. K. Sv. Vet Akad. Handl. Vol. 26, IV, No. 12, p. 24, figs. 48 .pi. 



This species is closely allied to M. Sabini, but much smaller. My largest specimens (from StaL 

 113) are a female with marsupium measuring 52 mm. and a male 51-3111111. long. Ohlin's largest male 

 was 56 mm. Ohlin has made a careful comparison between the two species and pointed out a few 

 differences, one among them being found in the number of abdominal segments, and perhaps the best 

 character being the conical process on the ventral side of seventh thoracic segment in M mrgalura, 

 while in M. Sabini I find a broad and low protuberance with a longitudinal excavation. 



Occurrence. Taken by the "IngolP at three deep stations in the cold area. 



Far south of Jan Mayen: Stat 112: Lato75/N^ Long. 644' W., 1267 fath., temp, -f- ri; 2 spec 



StaL 118: LaL 6827' N., Long. 82o' W., 1060 fath., temp. -Mt>; 4 spec 

 StaL 113: LaL bfyC N., Long. 7o6' W., 1309 fath., temp. ^ it>; 7 spec 



Distribution. Sars enumerated M. megalura from five places, all in the cold area but far 

 from each other, in the sea between Norway Spitzbergen in the Hast, while the western limit is a 

 line from a little east of the Faroes to somewhat west of Spitzbergen, and between LaL 63! 7' N. and 

 LaL 77*58' N.; the depths from 1081 to 1710 fath., the temperatures from -f- ix> to -* 1-4. Ohlin recorded 

 it from a place west of Spitzbergen, LaL 78i9' N., 1434 fath., temp, r4- The species is the 

 most pronounced cold water form from the deep sea known to me among the Isopoda. 



Idothea J. C Fabricius. , 



In 18941895 Ad. Dollfus published a valuable treatise: Les Idoteidae des cotes de France, in 

 1 i-uille des Jeunes Naturalistes, III. Ser. 25' Annee, which ought to be consulted together with Sars' 

 work. In the following a separate copy is quoted. 



Five well-known species are represented in the material 



128. Idothea balthica Pallas. 



1772. Oniscus Balthicus Pallas, Spic Zool. IX, p. 67? PI. IV, fig. & 



! 1894. I dot fa tricuspidata Dollfus, 1. c, p. 7, figs. 19, fig. 10 B, fig. 10, 



! 1897. Idothta baltica G. O. Sars, Account, II, p. 80; PL 32. 



1905. Richardson, Monograph p. 364, figs. 394395 (with enormous synonymy). 



