144 BRITISH C0PEP0DA. 



contractility which modifies their form according to 

 the will of the animal. The use of these expansions 

 is unknown, but may probably, M. Hesse thinks, be to 

 act as points d'appui for the movements of the 

 creature, or to aid in removing obstacles from its 

 path. For my own part I find it difficult to believe 

 that these excessively delicate organs can be of much 

 use for such purposes, or to understand why, if they 

 are so used, they should be entirely wanting in so 

 many other species which live under the same condi- 

 tions. We must, I think, admit that their use is at 

 present quite unknown. 



[Notopterophorus elongatus, Buchholz. Beitrage zur 



Kenntniss der Innerhalb des Ascidien lebenden 



parasitischen Crustaceen des Mittelmeeres, p. 127, 



taf. viii, fig. 6, and taf. ix, fig. 6. 



One or two specimens, which, I have no doubt, were 



referable to this species, occurred amongst those sent 



to me by my friend the Rev. A. M. Norman, but 



they seem to have been lost during examination, and 



I am now, unfortunately, unable to figure or describe 



them.] 



Sub-family 3. Ascidicolin^, Nov. sub-fam. 



First and second thoracic segments coalescent; 

 abdomen composed in the female of five, in the male 

 of six segments. Matrical envelope formed by a 



