1904-1905-] Copepoda living as Parasites or Messmates. 199 



might be regarded as messmates, claiming a share of the food 

 carried along these passages to the various parts of the sponge. 

 If, on the contrary, they live chiefly in the large excitrrent 

 passages, they may then be rightly regarded as commensals or 

 mutualists, paying for their shelter by assisting in the removal 

 of the waste and effete matter which it is the purpose of these 

 passages to carry to the outside. 



Chcdina and this Suberites are the only two sponges I have 

 examined thoroughly, but it is highly probable that if others 

 were examined, they too might be found to harbour these 

 minute crustaceans. 



2. Copepoda found only on Alcyonium or allied species. — 

 Though Alcyonium is usually considered higher in the scale of 

 life than the sponges, the copepods associated with it and its 

 allies are decidedly lower than the commensals of the latter. 

 The Asterocheres of the sponge belongs to one of the more highly 

 organised groups of the Copepoda ; but Lamippe proteus, the 

 species so common on Alcyonium, digitatum, if not a true 

 parasite itself, is very closely related to species that are. 

 Lamippe proteus varies to some extent in its general appear- 

 ance, as implied by the name, but usually it is of a narrow, 

 elongated form; the body exhibits very little segmentation, 

 and the limbs, which appear to be rudimentary, are only one- 

 branched, and fitted merely for crawling or grasping. Two 

 species of Lamippe have been obtained in Scottish waters — 

 viz., Lamippe proteus Claparede, mentioned above, and Lamippe 

 Forhesi T. Scott, both being parasitic on Alcyoniicm digit- 

 atum. The first is apparently very common, but the other is 

 rare. 



The first species of Lamippe to be recorded was Lamippe 

 ruira, obtained on Pennatida rubra, a species of Sea-pen which 

 occurs in Bohus Bay, off the Bohustan coasts of ^Norway and 

 Sweden. The species was described by Bruzelius in 1859 in 

 ' Archiv ftir Naturgeschichte.' The Sea-pen on which this 

 Lamippe occurs is apparently absent from our seas, but Pen- 

 oiatula phosptlwrea is moderately common in some places, and 

 I have examined many examples of that species without find- 

 ing a single Lamippe. The species to be recorded next in 

 point of time was the Lamippe proteus mentioned above. This 



