Gatty Marine Laboratory^ St. Andrews. 261 



lamella is narrowed at its atlachment, broader and somewhat 

 truncated distally, the reverse being the case in N. longisetosa. 

 Instead of a distinct flap externally only a trace in the shajie 

 of a fillet occurs. The dorsal cirrus is less, while the branchia 

 is longer, though it is likewise curved inward. The spini- 

 gerous lobe is produced further outwards as a pointed process 

 and has a different angle. Moreover, the fillet guarding the 

 barred bristles is convex upwards. In the inferior division 

 the posterior lamella is considerably smaller, the spinigerous 

 lobe is longer and more acute, whilst anteriorly the upper 

 fillet is smaller. The ventral cirrus is smaller and less tapered 

 than in N. longisetosa. Both barred and slender bristles are 

 more slender than in the latter species, though in both the 

 transverse bars of the camerated bristles extend downward 

 till the full diameter of the shaft is reached. 



The seventh form is JSephtlnjs Johnstoni, Ehlers, which has 

 a shield-shaped head, a broad and somewhat convex anterior 

 border, a slender tapering tentacle at each angle, and an 

 oblique translucent patch at its base internally. The second 

 pair occur after a considerable interval. The proboscis has 

 rather long rows of papillae distally and a median cirrus 

 dorsally and ventrally. Between the rows at the aperture is 

 a simple papilla dorsally and ventrally. The anterior folds 

 or lips in front of the month are large. The dorsal lamella 

 has a similar curvature to that of N. ciliata^ but it extends 

 further outward, and only a trace of the rounded terminal 

 lobe appears. The setigerous region stands up prominently 

 and is smoothly rounded externally. No free flap to the 

 anterior fillet guards the barred bristles. The dorsal cirrus is 

 a variable filiform process. The branchia is not large and is 

 coiled externally. The ventral lamella is large and ovato- 

 lanceolate, and the ventral cirrus is lanceolate, larger than in 

 N. ciliata, considerably less than in N. longisetosa. The 

 capillary bristles are longer and less rigid than in the latter, 

 and the serrations are very fine, the long distal region being 

 smooth. The barred region in the anterior bristles is long 

 and slightly fusiform. 



Nephthys cirrosa, Ehlers (1868), is the eighth British 

 species, characterized by a seven-sided head, longer than 

 broad, with a pair of conical tentacles in front and a longer 

 latero-ventral pair after a considerable interval. A small 

 papilla (sensory) lies on each side of the head posteriorly. 

 Proboscis with the normal rows (twenty-two) of rather long 

 papillaj, each row liaving six or more papillte. Shorter 



