﻿CRl'STACIvA JIAI,ACOSTKACA. 



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were used, whereas those taken witli loo meters wire out are l)ut small and far from mature. The 

 structure of .S'. arcticjis, the good state of preservation of the specimens taken by the "Ingolf and 

 the observatious mentioned of the "Thor" show clearly that the species is not a bottom-form, but 

 lives pelagically; large to ver\' large specimens are however never taken near the surface, and the 

 largest are not met with, at least as a rule, abo\e a depth of about 250 fm. and tlie\' descend i^robably 

 a good deal lower. — The specimen taken by the "Ingolf at St. 140 has certainly been carried by the 

 Gulf Stream into the Norwegian Sea and has been taken in the warmer layers, as the species un- 

 doubtedly does not live at the great depths with temperatures below o in the cold area. 



Remarks. In my two papers owScrgestcs mentioned abo\e, I have dealt with the characteristics 

 of this species, its distribution, the list of synonyms and likewise some of its larval stages, of which 

 one has been described as Srrgcstcs Riiikii Kr. The largest "Ingolf specimen came from vSt. 9 and 

 measures 55 mm. 



79. Sergestes robustus vS. I. Smith. 



! 1882. Sergestes robustus S. I. Smith, Bull. .Mu.s. Comp. Zool., Vol. X, No. i, p. 97, PI. XVI, figs. 5—8 b. 

 18S6. — — S. I. Smith, Rep. Comm. Fish & Fisher, for 1885, p. 697, PI. XX, fig. 6. 



1^03. — — H. J. Hansen, Ann. and Mag. Nat. Hist, Ser. 7, Vol. XI, p. 480, figs. 6^7. 



— — iuermis H. J. Hansen, Ann. and Mag. Nat. Hist, Ser. 7, Vol. XI, p. 479, figs. 1—5 (barely 



half-grown specimen). 



Occurrence. The "Ingolf" has not taken this .species, but I have seen specimens from the 

 following place. 



South-West of the Fceroes: 6i''o8'N. L., 9° 46'W. L., 450 fm., 3 specimens taken by the "^Michael 

 Sars" CVs 1902) and belonging to the Bergen Museum. 



Distribution. It has been taken at 59"49' N.L., 9"46'W. L. b\- the "Thor", at 52°4'/; X. L., 12" 27' W'.L. 

 (Hansen), in the Mediterranean (Han.sen) and at a number of places off the east coast of North America 

 between 4iV3° and 34" 28' N. L., in depths from 372 to 2574 fm. In the "Sunnuary of the Deep-Sea 

 Zoological Work of the Royal Indian IMarine Survey Ship "Investigator" from 1884 to 1897", 1899, 

 p. 30, Alcock writes concerning this species: "Off coasts of South-India and Ceylon 200—902 fathoms 

 (common)"; but it is somewhat remarkable that he does not mclude it in his "De.scriptive Catalogue 

 of the Indian Deep-vSea Crust. Dec, Mac. and Anomura, 1901". 



Remarks. The largest specimen from the localit>- mentioned was 60 mm. long when scarcely 

 fully extended. The specimens agree ver>- well with a specimen determined l)y Smith received from 

 the U. S. Nat Museum. The specimen from the "Thor" is 90 nun. li)ug. 



It appears from the list of s\-uou\'ms, that I now consider the .S'. iiicnuis founded by me in 

 1903 on a single not quite half-grown specimen as a young stage of .S". rohiistHS shortly after the 

 larval period. I have come to this result from a study of a considerable nuUerial from the Monaco 

 Museum, from E. Holt, and from the "Travailleur" and "Talisman". The rea.sons for my considering 

 in 1903 the differences between an adult specimen of S. robustus aiul the specimen described as 

 ,V. iiicriiiis to be .specific differences, arose in the first ])lace from the complete lack of transitional 

 stage.s, and in the second from the fact that our !\[u.seum po.s.se.sses some phnnp specimens, some of 



