158 



Part II L — Sixteenth Annual Report 



.(1) The months in which 1 



the capture of Deca- > Jan. Feb. Mar. Aug. Sept. Oct. Xov. Dec. 



poda are recorded J 

 Number of records for 1 



each of the months 17 17 6 3 7 1 4 1 



for the seven years J 

 '(2) The Stations where] 



the Decapoda were I I. III. IV. V. YIII. IX. 



captured J 

 Number of records f or | ^ ^ ^ ^ ^ ^ ^ 



each station J 



The number of records for February alone is 1 7, or 27 per cent, of the whole ; 

 and the number for the five colder months, January, February, March, 

 November, and December, is 35, or fully 76 per cent. The reason that 

 these Decapods are found usually in the bottom tow-nets, and not in those 

 worked at the surface, is that they are veritable bottom feeders ; and were 

 it not for their peculiar habit of springing upward as well as backward 

 when disturbed, their capture would be much less frequent. When any 

 suspicious object is approaching these Crustaceans (I refer to the Carida 

 or " shrimp " group) they face round towards it and intently watch its 

 movements, and at the same time swim gently backwards, or they may at 

 once bury themselves in the sand or mud. If the danger, however, 

 should approach them suddenly, they spring quickly backwards and also 

 obliquely upwards, and it is then that they come within the sweep of the 

 bottom tow-net. But though the occurrence of these organisms in the 

 bottom tow-net may be thus more or less satisfactorily explained, the 

 reason for their being captured chiefly during the colder months seems to 

 be less easy of explanation. It may be observed, however, that only five 

 of the records are for the inshore station, and that about half of the total 

 number are for Stations III. and Y., the two stations in the middle of the 

 estuary, the one extending east from Inchkeith the other west from May 

 Island. 



{h) SCHIZOPODA. 



The Schizopoda are well represented as regards the number of species, 

 and a few of them, especially those of the Eiiphausiidse, appear to have 

 been at times pretty numerous at the station under consideration. The 

 Scliizopods referred to in the records and distinguished by their names are 

 the following : — * 



EUPHAUSIID^E. 



Boreophausia rascliii{^\. Sars). Thysanoessa negleda (Kroyer). 



MYSIDJE. 



Siriella jaltensis, Czern. ( = Siriella Leptomysis gracilis, G. O. Sars. 



crassipes, G. O. Sars). ,, Uiigoura, G. 0. Sars. 



„ armata (M. Edw.). Hemimysis lamornfje (Couch). 



Gastrosaccus spinifer (Goes). Macropsis slahheri (Van Ben.). 



Heferomysis formosa, S. I. Smith. Praunus flexuosus (Mtiller). ( = 

 Erythrops go'esii, G. 0. Sars. Mysis cliamoileon, Varg.). 



Mysidopsis didelphys (Norman). „ inermis (Rathke). 



„ gibbosa, G. 0. Sars. Schistomysis spiritus, Norman. 



„ angusta, G. 0. Sars. ,, ornata (G. 0. Sars). 



Neomysis vulgaris (J. V. Thompson). 



* The names and their arrangement are in accordance with' Rev. A. M. Norman's 

 revision of the British Schizopoda, published in the ' Annals and Magazine of Natural 

 History' for June, August, and September 1892. 



