Ig2 CRUSTACEA MALACOSTRACA. III. 



the second, though in reality not small and easily seen when second pair are lifted; fifth pair are 

 even rather large. The genus Pleuroprion is closely allied to Arcturus; in P. Murdochi Ben. I have 

 without difficulty found five pairs, the fifth being somewhat smaller than in Archirus; in P. hystrix 

 G. O. S. the same number is found, but P. frigidum n. sp. differs in having only four pairs, as it is 

 easily seen that the pair of fifth legs are wanting. 



Then Astacilla. The first correct statement on the marsupial plates is due to Bonnier, who in 

 1896 described and figured four pairs in Astacilla Giardi Bonn., in 191 1 established by Koehler as a 

 new genus, Arcturopsis. The last-named author examined Astacilla longicornis Sow., A. granulata G. O. S., 

 A. Deshayesii Luc, Arcturella danmoniensis Stebb. and a number of new species belonging to the same 

 genera and to two new genera; he found everywhere three pairs of lamellae belonging to second to 

 fourth pairs of legs. Stephensen (1915) found four pairs of lamellae in his Astacilla^) Bonnieri Steph., 

 but only three pairs in A. longicornis Sow. In A. longicornis, A. granulaia and in Danish specimens 

 of Arcturella dilatata G. O. S. I have found four pairs, and the first pair, belonging to first pair of 

 legs, are somewhat small but always distinct; I am sure that the same number exists in all European 

 species of Astacilla and allied genera. 



ArcturUS Latreille. 

 The material comprises only a single species, but according to Norman a second form has been 

 found near the Faeroes. 



134. Arcturus Baffini Sabine. 

 (PI. XV, fig. 5 a). 

 1824. Idothea Baffini Sabine, Suppl. to the App. to Capt. Parry's Voyage, p. 228; PI. I, figs. 4—6. 

 ! 1885. Arcturus Baffini G. O. Sars, North-Atl. Exp., Crust. I, p. 97; PI. IX, figs. 1— 21. 

 ! — tuberosus G. O. Sars, ibid. p. 102; PI. IX, fig. 22. 



!8 9 5. — Baffini Ohlin, Bidrag til Kami, om Malakostrakfaunan i Baffin Bay och Smith Sound, p. 15. 



Ohlin's book contains much information on variation among specimens. - - The largest spec- 

 imen seen by me is from East Greenland, Eat. 72°53' N., and is 56-5 mm. long; Norman recorded a 

 specimen to be 60 mm., and Miers a specimen from Grinnell Laud, at Lat. 79°29' N., as being 66 mm. 

 Occurrence. Taken by the "Ingolf at seven stations. 

 Davis Strait: Stat. 31: Lat. 66°35' N., Long. 55°54' W., 88 fath., temp. r6°; 3 spec. 



— Stat. 34: Lat. 65°i7' N., Long. 54°i7' W., 55 fath.; 2 spec. 

 West of Iceland: Stat. 87: Lat. 65°02' N., Long. 23°56' W., no fath.; 2 spec. 

 Between Iceland and the Faeroes: Stat. 4: Lat. 64°o7' N., Long. ii°i2' W., 237 fath., temp. 2-5°; 



14 spec. 

 Stat. 3: Lat. 63°35' N., Long. io°24' W., 272 fath., temp. 0-5°; 



14 spec. 

 _ _ _ Stat. 2: Lat. 63°04' N., Long. 9°22' W., 262 fath., temp. 5-3°; 



many specimens; most of them are young. 

 North of the Faeroes: Stat. 143: Lat. 62°58' N., Long. 7=09' W., 388 fath., temp. ^0-4°; 2 spec. 



