66 COPEPODA 



Some of the differences are certainly congenital, but others are probably due to the fact that 

 specimens, which later on are found under identical biological conditions, are born at different localities 

 and have got a different start hi life, before being carried by currents or other agencies to their 

 present abode. 



ii. Microcalanus pygmaeus G. O. Sars. 



1900. Pseudocalanus pygmaeus 11. sp. (9) G. O. Sars, pp. 73 75 i 1907. Pseudocalanus pygmaeus G. O. Sars. Damas and Koefoed, 



pi. XXI. pp. 396 and 407. 



Spinocalauus longicornis n. sp. (d 1 ) G. O. Sars, pp. 77 1908? Microcalanus sp. Farran, p. 28. 



78, pi. XXII figs. 1314. 1908. pygmaeus G.O. Sars. v. Bremen, p. 26 fig. 24. 



1901. Pseudocalanus pygmaeus G. O. Sars. Th. & A. Scott, ' pusillus G. O Sars. v. Bremen, p. 27 fig. 25. 



p. 339. 1908? Wolfeuden, pp. 41 42, 



1902. Mrazek, pp. 508 pi. II fig. 5. 



509, taf. V figs 3 ii. | 1908? Hj. Brock. 



1902? G. O. Sars. Giesbrecht, p. 20, 1910? Kraeeft, pp. 98 99. 



taf. 2. i 1911? Farran, pp. 98 99. 



1903. Microcalanus pygmaeus G. O. Sars. G. O. Sars, p. 157. i 1911? Wolfendeu, p. 286. 



? Microcalanus pusillus n. sp. G. O. Sars p. 156 157; sup- 1913. pygmaeus G. O. Sars. Stephensen, pp. 311 



plement pi. II, pi. Ill fig. i. 312. 



Description, f !j>. Most of the examined full-grown females agreed fairly well with Sars' descrip- 

 tion of M.pygm&us. The size of the specimens varied from 0-65 to 0-9 mm. In a single specimen (St. 8) 

 the antennulae scarcely reached the end of the first abdominal somite, and the terminal spine of the second 

 pair of legs of this, as well as of other specimens, had indication of the serration which according to 

 Sars forms the chief characteristic between M. pygmceus and pusillus; as the natatory limbs were 

 broken in most of my specimens, I was unfortunately unable to examine this character in most spec- 

 imens (cf. pag. 68). According to Sars the rostrum is represented by two "extremely small tentacular 

 filaments"; in my specimens, as in those examined by Mrazek and Kraeeft, these organs are 

 rather thick and more like teeth. 



fc?. Size: i-i mm. The structure of the fifth pair of legs is very much like that figured by 

 Sars (PI. I pes V <?), but in my specimen the division of the left leg into 3 basal segments is more 

 indistinct. 



Y (St. V). The juniores (<$ $ Copep. V) are practically like the preceding stage, but for the 

 number of abdominal somites. The male differs from the females by less prominent first abdominal 

 somite and a fairly well developed fifth pair of legs (cf. Mrazek fig. 13). 



Y (St. IV): Size: (?) 0-65 075; (c?) 0-65 0-9 mm. In this stage with only 3 abdominal somites 

 are the same differences between males and females observed. 



Occurrence. Considering its minuteness one can not wonder that this species has only been 

 taken from the following few stations by the Ingolf Exp. 

 Davis Strait: St. 29. 6534 L. N. 543i I v . W. */? 3.30 p. m. 1895. V 1 . 50 ofm. Temp, at surface 3-5 



C. i?, ic?, 4 y?(V), 8y<?(V). 

 West of Iceland: St. 95. 65i4 L. N. 3o2g I/. W. 2 ?/6 5-25 p.m. 1896. P. 100 ofm. Temp, at surface 7-8 



C. 16?, 5Y?(V), 26yc?(V). 



St. 8. 63s6 L. N. 24^0 L. W. '9/ 5 5 p.m. 1895. V. ico-ofm. Temp, at surface 8-6 



C. i?. 



