CRUSTACEA MALACOSTRACA. III. i8j 



M. Sabini has thus been taken in depths from 4 to 197 fath.; according to Stuxberg the tem- 

 perature at the bottom was generally between -=- 0-4° and H- 17°, while small specimens have been found 

 in so high a temperature as 2 - 6°. 



127. Mesidothea megalura G. O. Sars. 



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

 ! 1885. Glyptonotus megalurus G. O. Sars, North-Atl. Exp. Crust. I, p. 112; PL 10, figs. 1 — 23. 

 1901. Chiridothea megalura Ohlin, Bill. K. Sv. Vet. Akad. Handl. Vol. 26, IV, No. 12, p. 24, figs. 4 a — 4d. 



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

 113) are a female with marsupium measuring 52 mm. and a male 51-3 mm. 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. megalura, 

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



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

 Far south of Jan Mayen: Stat. 112: Lat. 67°57' N., Long. 6°44' W., 1267 fath., temp. -=- ri°; 2 spec. 



Stat. 118: Lat. 68°27' N., Long. 8°2o' W., 1060 fath., temp, -f- ro°; 4 spec. 

 — — - Stat. 113: Lat. 69°3i' N., Long. 7°o6' W., 1309 fath., temp, -f- ro°; 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 East, while the western limit is a 

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

 Lat. 77°58' N.; the depths from 1081 to 1710 fath., the temperatures from -=- ro° to -f- 1-4°. Ohlin recorded 

 it from a place west of Spitzbergen, Lat. 78°i9' N., 1434 fath., temp. -=- 1-4°. — The species is the 

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



Idothea J. C. Fabricius. 



In 1894 — 1895 Ad. Dollfus published a valuable treatise: Les Idoteidse des cotes de France, in 

 Feuille des Jeunes Naturalistes, III. Ser. 25 e 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; PL IV, fig. 6. 

 ! 1894. Idotea tricuspidata Dollfus, 1. c, p. 7, figs. 1—9, fig. 10 B, fig. 19. 

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



1905. — — Richardson, Monograph p. 364, figs. 394—395 (with enormous synonymy). 



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