PELAGIC FAUXA OFF THE WEST COAST OF ARRAN. 



and an exquisite trochophore larva — a typical " Loven's Larva." 

 This latter attracted attention at once by its conspicuous differ- 

 ence from the Mediterranean Polygordius larva described by 

 Hatschek, in the fact that the trunk region developed within 

 the body of the larva, as described by Woltereck for the North 

 Sea type of Polygordius. I have submitted a specimen to Prof. 

 Woltereck, who is our chief authority on the larva of Poly- 

 gordius, and he assures me that the Blackwaterfoot larva belongs 

 to the North Sea form, Polygordius lacteus. The Polygordius 

 trochophores were got in large numbers at the surface on 25th 

 September, with a light northerly breeze off the land. They 

 were first got on 18th September. 



Mitraria. — This interesting form, which is stated by Watson to 

 be the larva of Owenia Jlliformis, D.Ch., appeared in the tow-net 

 on 6th September. The specimen obtained appears to come closest 

 to M. skifera, Hacker, which was obtained by the Plankton 

 Expedition in the Atlantic, about 200 miles west of the Hebrides. 

 It differs, however, from this " species " in that the chief chaetae 

 have sharper points, and that the needle-shaped chaetae are much 

 longer. 



It should be noted that, although Mitraria is not included 

 in the British Association fauna list, it was obtained by Claparede* 

 in September, 1859. in Lamlash Bay. The specimen obtained 

 by Claparede differs considerably from the Blackwaterfoot speci- 

 men, and would probably be looked on by describers of Mitraria 

 as a different species; but it appears very inadvisable to accord 

 specific rank to such larvae as these until we are acquainted 

 with their life-history, and with the changes which take place 

 in their characters during development. 



Besides various Spionid and other larval Polychaetes, various 

 adult forms of pelagic habit appeared from time to time in the 

 tow-net. 



Tomopteris occurred on various occasions, especially about the 

 middle of September. The sexual individuals of Autolytus 

 prolifer, both male (" Polybostrichus ") and female (" Sac- 

 conereis "), occurred occasionally along with those of at least 

 two other species of Autolytus. Amongst these should be 



* Zeits. wiss. Zool. Bd. X. s. 407. 



