CRUSTACEA MALACOSTRACA. 103 



character of Arctomysis thus falls to the ground; the species of Kroyer and Sars are identical, which 

 has also been accepted by Sars himself and by several other observers. 



9. Boreomysis microps G. O. Sars. 



1883. Boreomysis microps G. O. Sars, Forh. Vid. Selsk. Christiania for 1883, No. 7, p. 35. 

 1885. G. O. Sars, Challenger Rep., Zool., Vol. XIII, p. 185, PI. XXXIII, figs. 7-10. 



! 1905. subpellucida H. J. Hansen, Bull. Mus. Ocean. Monaco, No. 30, p. 8, figs. 58. 



Occurrence. The "Ingolf" has not found this species but it was taken by the "Thor" in 1904 

 at the following localities. 



West of Iceland: 65 oo' N. L,., 28 10' W. L., 1240 m., Young-fish trawl, 1000 m. wire out; many spec. 

 65 20' 27i2 I / 2 '- 740 m., 8iom. 6 spec. 



- 65 27' 27 lo'/z' - 763 m., 800 m. 2 

 South of 6i34' 19 05' 2160 m., 1800 m. 7 



- 61 30' 17 08' ? 1800 m. many spec. 



62 47' !$" 3' 1950 m., icoo m. i spec. 



South-West of the Faeroes: 61 08' N. L., 9 28' W. L-, 820 m., Young-fish trawl, at bottom ; i spec. 



Distribution. The species was founded on a specimen taken south of Nova Scotia: 62 8' N. L., 

 63 39' W. L., 1250 fm. The "Thor" has taken it 3 times in the waters west of the Hebrides with the 

 young-fish trawl, 1500 meters wire out. It was next taken to the west of Ireland in townets from 

 1150 to o fm. (Holt & Tattersall), also at several places south of the Azores in the vertical net sunk 

 to 16401770 fm., once to 820 fm. (Hansen). The species thus belongs to the mesoplankton and as a 

 rule is scarcely met with before ca. 200 fm. down, but how deep it penetrates is naturally unknown. 



Remarks. In my paper cited, I founded a new species B. subpellucida, as the numerous 

 specimens I had differed considerably from Sars' descriptions and figures in some characteristics. Thus 

 Sars has neither mentioned nor figured the very distinct process on the upper side of the eye-stalks 

 close behind the cornea, also the proximal part of the telson is considerably narrower in relation to 

 its length than in my specimens. Later Mr. Holt examined Sars' type preserved in the British Museum 

 and writes (in 1906): "The fact is that in so far as the diagnosis of B. microps differs from that of B. 

 subpellucida, the former is erroneous"; consequently he withdraws B. subpellucida as a synonym to B. 

 microps. My own examination of Sars' type in 1906 gave the same result. 



A large female with marsupium (from 65 N. L,.) measures 20 mm. from tip of rostrum to end 

 of telson; a male from 6i I / 2 N. L,. is 19-5 mm. long. 



10. Longithorax fuscus n. sp. 



PI. V. figs, i a i o. 



Description of the Genus. As the description of the genus is founded on a single somewhat 

 damaged female, in which the marsupium is not fully developed, this diagnosis is not quite complete 1 . 



1 I had established a new genus on the present form before Dr. G. Illig's preliminary note on the "Valdivia" Mysi- 

 dacea was published. Consequently I accepted the generic name Longithorax proposed by him for an allied species, but I did 

 not alter anything in the descriptions of the genus or the species. 



