Gaily Marine Laboratory, St. Andrews. 47 



4. On the Chcetopteridoe, Ampliictenidse, and Ampliaretidae 

 dredged in the Gulf of St. Lawrence, Canada, hij 

 Dr. JV/iiteaves in 1871-73. 



The Clisetopterids are represented only by fragments of a 

 Spiochcetopterus, probably S. typiciis, Sars, from No. 9, 1873. 



Tlie Amphietenidfeinclude Cistenides hyperborea, INIalmgren, 

 dredged in 100-212 fathoms off Anticosti in 1871 and more 

 abundantly on Orphan Bank^ Nos. 9 and 16, 1873. This 

 form is distinguished by the dark colour of the paleolse 

 and their number — viz. twelve to fourteen, thougli occasion- 

 ally fifteen may be present, — by their greater breadth than in 

 Lfiffis, and tbougli the tips are finely tapered they are more 

 rigid than those of Layis horcni^ by the peculiarly blunt, 

 almost knob-like, condition of the fringes of the veil, and by 

 the presence of seventeen pairs of bristle-bundles. One of 

 the most characteristic features anteriorly is the oral A^eil, 

 which, instead of ceasing laterally in a line with the anterior 

 cirrus, passes downward and backward as a broad sheath, 

 which envelops niost of the oral tentacles like a broad funnel, 

 as in CistenidiiS yranulata, a form characteristic of the waters 

 of Greenland. This has similar papillae on the margin of the 

 veil, but only nine or ten paleolse in its crown. The anterior 

 and posterior bristles closely resemble those of Layis koreni, 

 though, on the whole, the stronger anterior (simple) bristles 

 have broader shafts in the latter. The caudal hooks of the 

 Canadian species are less tapered at the neck, the curve 

 of the terminal hook less marked, and the point in tlie 

 British form is also often sharper. One of the most 

 distinctive features, however, is the structure of the minute 

 hooks (PI. II. fig. 7) on the lamellae of the feet, which, 

 instead of having six teeth in a continuous row above the 

 minute series of four inferiorly, have but three in increasing 

 size, The process beneath the third usually has three teeth 

 at the tip, as shown by Malmgren, but sometimes four occnr, 

 and occasionally only two — apparently from injury. The 

 groove below this process is figured by Malmgren as bluntly 

 and smoothly rounded, but it really shows from above down- 

 ward a convexity and then a concavity, with a small hook- 

 like tip. The shaft diminishes even more rapidly than in 

 Layis koreni. The anal process has three or four lobes on 

 its dorsal margin behind the hooks, and thus differs from 

 that of Layis koreni, which has a papilla on the tip of these 

 proces.«;es. 



Stalked Infusoria occnr in numbers on the paleolae. 



