196 SPOLIA ZEYLANICA. 



difference such as this might easily be accounted for by the 

 greater preponderance of females in the catch. 



With regard to the total number of hairs affected and their 

 relative position, it is quite clear that on the whole far more 

 setse are abnormal in the female than in the male, and, further, 

 the setse most frequently affected are those that possess the 

 greatest length, i.e., numbers 2, 3, and 4. 



I have on one occasion found a similar " plumose " seta 

 arising from the tip of a damaged antenna in an example of 

 Acrocalanus longicornis. In this case the antenna had 

 obviously been damaged on some previous occasion, the 

 terminal segments being broken off ; subsequently the stump 

 had healed, and from the scar this seta had arisen. 



I am of the opinion that this plumose modification is an 

 abnormality produced by injury to, and subsequent re- 

 generation of, the seta, and, further, the prevalence of this 

 change in spermatophore -bearing females of Undinula vulgaris 

 would tend to show that the injmy is frequently caused during 

 the act of deposition of the spermatophore by the male. 



Genus Undinula, Scott. 



Undinula vulgaris (Dana). 



(PI. XVII., figs. 1 and 2.) 



Calanus vulgaris, Giesbrecht, 1896, p. 318. 



Thompson, 1899, p. 275. 



Cleve, 1901, p. 5. 



A. Scott, 1902, p. 400. 



Thompson & Scott, 1903, p. 357. 



Cleve, 1903, p. 357. 



aeve, 1904, p. 186. 



Wolfenden, 1905, p. 994. 



Undinula vulgaris, A. Scott, 1909, p. 16. 

 Sewell, 1912, pp. 315 and 356. 



Calanus vulgaris var. plumulosus, Wolfenden, 1905, p. 994. 

 PI. XCVI., figs. 21, 22. 



Undinula vulgaris var. plumulosus, Sewell, 1912, p. 356. 



