364 Copepoda living as Messmates with Ascidians. [Sess. 



been observed. Adult specimens measure fully two milli- 

 metres in length. The furcal segments are long and slender, 

 and are about one-fourth of the entire length of the animal. 



Doropygus auritus Thorell appears to be a moderately large 

 species, reaching, in the case of adult females, to one-fifth of 

 an inch in length. It has been recorded from Shetland by 

 Eev. A. M. Norman, who obtained it in Ascidia (Phcdlusia) 

 mentula 0. F. Miiller. This species differs from D. pulex in 

 having very short tail-segments. 



Doropygus Normani G. S. Brady is described as moderately 

 common in large Ascidians. The length of adult females is 

 stated by Dr Brady to be 3*3 millimetres. The tail-segments, 

 though short, are distinctly longer than in the last species. 

 This form has been obtained in the Firth of Forth off Mussel- 

 burgh in the branchial chamber of large Ascidians (? A. 

 virginea 0. F. Miiller). 



Doropygus porcicauda G-. S. Brady. — This species is not 

 much inferior in size to D. auritus, the length of adult 

 females described by Dr Brady being about four millimetres. 

 It has been obtained in Corella parallclogramma dredged off 

 the coast of Durham, and in large Ascidians dredged in Loch 

 Fyne and at Birterbuy Bay, Ireland. I have taken what 

 appears to be the same species in the Firth of Forth. This 

 species, as implied by the name, is a robust form ; the tail- 

 segments are also moderately elongated. 



Doropygus gibber Thorell has been recorded from Exmouth, 

 from the pharyngeal cavity of Ciona intestinalis, 1 and Dr 

 Canu describes it as very common in many of the Ascidians 

 of the Boulogne littoral. The females of D. gibber are de- 

 scribed as reaching to five and six millimetres in length. 

 This species has been ascribed to the genus Notopterophorus 

 by Giesbrecht and Canu, but as the wing-like dorsal expan- 

 sions, which are apparently the chief distinguishing character 

 of that genus, are entirely wanting, I have retained it in the 

 genus to which it was originally assigned by M. Thorell. 



Doropygus psyllus Thorell is a rare form, and has not yet 

 been observed in British waters. I refer to it here because, 

 according to Dr Brady, it seems to be very nearly allied to 



1 "The Fauua of the Exe Estuary," by E. J. Allan and R. A. Tod, 'Jour. 

 Plymouth Marine Biol. Assoc.,' vol. iv. (N.S.), No. 3, p. 325 (1902). 



