84 CRUSTACEA MALACOSTRACA. 



which are in the Mastigopus-stages, others a little more advanced in development, and these I had 

 taken to be the developmental stages of S. robustus, but according to my later observations these 

 must belong to a species which is not known at any rate from the Atlantic. 



In 1896 I founded S. mediterrancus on several specimens, in the largest of which the eyes 

 were not yet black, while the others were Mastigopus-iorms. In 1903 I included 6'. mcditcrranctis as 

 a synonym under S. dissimilis Bate. It appears now that S. dissimilis is the Mastigopus-stagz of 

 .5". robustus, so that intermediate stages have been described as S. incertus H. J. H. and as "the sub- 

 adult stage" of S. mediterrancus H. J. H. 



II. Order: Euphausiacea. 1 



Within the region, the fauna of which is dealt with here, only 10 species in all have been 

 taken of this Order 2 . As nearly all have been so well described and figured that they can be recognised 

 with certainty, my notes are made relatively fairly short, the more so as I intend in the near future 

 to publish a monograph of the whole Order based on an extremely large material. Analytical figures 



etc. will be much more suited to such a monograph and of more use there than if they were given here. 



I 



i. Thysanopoda acutifrons Holt & Tatt. 



1905. Thysanopoda pectinata H. J. Hansen, Bull. Mus. Ocean., Monaco, No. 30, p. 16, Fig. 12 (nee 



T. pectinata Ortmann). 

 1905. acutifrons Holt & Tattersall, Rep. Sea and Inland Fisheries of Ireland, 19021903, 



Part II, App. No. IV, p. 102 and 134 (immature specimens). 



1905. H. J. Hansen, Bull. Mus. Ocean. Monaco, No. 42, p. 22. 



! 1906. Holt & Tattersall, Fisheries, Ireland, Sc. Invest. 1904, V, p. 8, PI. I. 



Occurrence. The "Ingolf" took this large species in the trawl at 4 stations: 

 West of Iceland: St. 12: 64 38' N. L., 3237'W. L., 1040 fm.; i spec. 



- 9: 64 18' 27 oo' 295 -; i 



South-West of Iceland: St. 17: 62 49' N. L., 26 55' W. L., 745 fm.; 2 spec. 



- 83: 62 25' - 28 30' 912 -; 2 



1 I see no reason for following Stebbing and call this order Thysanopodacea because the oldest of the genera has 

 the corresponding name. If an author (in casu J. Boas) has set up a group as order or family given it a name and 

 for that purpose used one of the genera of the group as basis, this name chosen by the author of the order or family has 

 priority and should be maintained unless the name of the genus in question must be dropped. Just as it is necessary 

 (so far as it is possible within reasonable limits) to maintain the oldest names for species and genera, we must also go upon 

 the same principle in retaining the oldest name for a family or order irrespective of how it was formed; in this way we have 

 more stability than on any other method of procedure. It is another matter, that in forming a family it would be best to 

 use immediately the oldest generic name as family name. 



2 Ortmann in his work on the Schizopoda of the Plankton-Expedition has stated that Thysanopoda microphthalma 

 G. O. S. is present from the Irminger Sea (at 60 N. L.). According to the form and equipment of the antennae as shown in 

 the author's figure his determination is incorrect, and I think he has had small specimens of T. acutifrons Holt & Tatt. which 

 is not rare in these waters. 



