352 TRANSACTIONS, NATURAL HISTORY SOCIETY OF GLASGO\V. 



Several specimens on the zostera-bed near low- 

 water, Tarbert (Brook). This species is a native of 

 the Mediterranean, and has not hitherto been re- 

 corded from the British seas, though Dr. Norman 

 has previously received specimens taken by Mr. 

 Parker at Starcross, Devonshire. 



Genus Gastrosaccus, Norman. 

 Gastrosaccus, Norman, Rep. Brit. Assoc, 1868, p. 268. 



GASTROSACCUS SPINIFER. 



Mysis spinifera, Goes, Crust, decap. mar. Sueciae, p. 14. 



Gastrosaccus sanctus, Norman, Rei^. Brit. Assoc, 1867, p. 438; 

 I.e. 1868, p. 268. 



Gastrosaccus spinifer, Stebbing, Ann. Mag. Nat. Hist. ser. 5, 

 vol. vi., 1880, p. 114, pi. iii. 



Firth of Clyde (Robertson). This mysid is well 

 figured and described by the Rev. T. R. R. Stebbing, 

 who first pointed out that it is distinct from 

 Gastrosaccus sanctus (Van Beneden), to which species 

 it was doubtfully referred by Goes and Norman. 



APPENDIX. 



It is to be understood that all remarks made in 

 the foregoing list have been founded on the 

 examination of Clyde specimens, though they will 

 probably also be found applicable to those from 

 other localities. The classification adopted in the 

 Decapoda is that of Prof. Dana in his great work 

 on the Crustacea of the United States Exploring 

 Expedition, and in the Schizopoda the arrangement 

 of Prof. G. O. Sars has been followed. 



The higher Crustacea probably spawn at least 

 twice in the year, viz., in spring, and in summer or 

 autumn, the exact period being determined by con- 

 ditions such as abundance of food, temperature, &c. 

 The month, therefore, in which a female is found 

 with ova in one year may differ in the next, so that 

 only an approximate idea of the season is obtainable. 



