Oatty Marine Luhoratorij ^ St. Andrews. 21 



groove a firm process of siinihir tissue passes straight down- 

 ward and bifurcates after a short course, its suiuniit giving 

 origin to two short curved Haps like a bifid epistome over- 

 hanging the nH)Uth, which appears as a triradiatc fissure 

 with two pouting membranous lobes infcriurly. By the 

 sides of tlie dorsal groove are two thick firm ridges — 

 apparently fused with the basal semicircles supporting the 

 branclii;e. From the outer base of each of these the collar 

 arises by a thick eiieular flap, from which the large lateral 

 division passes forward and downward to end in a smaller 

 thick attachment at the side of the anterior process of the 

 ornamental (scano|)cd) first scute. This lateral fhip is 

 slightly tinted in the pn-paration, but in the living form is 

 of the same deep violet-brown bordered with white. Over- 

 lapping the ventral edge of this lamella is the ventral plate, 

 which curves downward and extends on each side of the 

 middle line into a triangular refieeted flap — the anterior 

 surface of the whole being of a rich deep brownish purple, 

 bordered with white. If the base of the s(^parated branchial 

 system be examined, a facet marks the dorsal end of each of 

 the semicircles of firm tissue of attachment, and the facet 

 fits on the firm pillars on each side of the dorsal furrow. 

 The firm basal mass of each branchial fan is bridged on the 

 ventral side of the facets l)y a narrow but firm band. From 

 the ventral aspect the basal mass on each side curves forward 

 and inward to end in a thick inrolled edge in the centre of the 

 spire. In the middle line and attached by its basal webs 

 to the bridge of connecting-tissue, on the one hand, and the 

 dorsal edge of the base of the fan, on the other, is the ten- 

 tacle on each side. These webs are of importance in the 

 directing-cnrrents, and the ventral is incurved. The ten- 

 tacle is short, broad at tlie base, and tapered. The exterior 

 of its base is tinted brown, and a ridge formed apparently by 

 the prolongation backward of the thickened margin of the 

 Hap guarding the dorsal edge of the channel from the centre 

 of the spire keeps the base of the tentacle stiff. From the 

 firm spiral base the branchial filaments pass forward to the 

 number of forty-five to eighty on each side, the number 

 apparently increasing with age. They are united at the 

 base by a short web, and are comparatively long. Each 

 filament has the camcrated axis which extends to the base of 

 the terminal process, but does not seem to enter it, for only 

 an opa(pie granular central region with a short web at each 

 side is present. On the outer edge of many a pair of 

 well-marked pigmcnt-spccks, and in some two or thiee, but 

 their position is irregular ; where three occur, the lirst is a 



