43 



oval in form, unequally trilobate at the end, the outermost lobe occurring far in 

 front of the innermost one; appendicular bristle very strong, spiniform, and, as 

 in P. acuta, issuing from the lower face of the proximal joint; inner expansion 

 of the latter rather narrow, and extending somewhat beyond the middle of the 

 distal joint, outer apical spine very small. 



Colour yellowish brown. 



Length of adult female 0.59 mm. 



Remarlfs. This form, the identity of which with Brady a similis of Scott 

 I cannot doubt, may be easily distinguished from any of the 2 preceding species 

 by the remarkably prolonged caudal rami, in which respect it agrees with 2 other 

 species described by Mr. Scott, viz., P. elegans and P. hirsuta. It is, however, 

 of much smaller size than either of these species. 



Occurrence. Only 2 specimens of this form were found last summer, 

 together with the 2 preceding species at Selven, Trondhjem Fjord. 



Distribution. Firth of Forth (Scott). 



Gen. 11. MiCFOSetella, Brady & Robertson, 1873. 



Generic Characters. Body very slender, with the anterior division scarcely 

 broader than the posterior. Cephalic segment projecting in front in a short, de- 

 flexed rostrum. Epimeral plates of this and the 3 succeeding segments well 

 developed, partly including between them the oral appendages and the basal parts 

 of the natatory legs. Caudal rami short, with the 2 middle apical setae greatly 

 elongated. Anterior antennae slender and elongated, with only scattered bristles; 

 those in male distinctly geniculate, terminal part rather prolonged. Posterior 

 antennse with the outer ramus much shorter and narrower than the inner, 3-arti- 

 culate. Anterior lip not produced in front. Mandibles with the palp very large, 

 distal joint spatulate in form and about the size of the proximal one, carrying 

 at the lower edge a remarkably strong spiniform seta, clothed along one of the 

 edges with long cilia; outer ramus very small. Maxillae of more simple structure 

 than in Ectinosoma, the palp apparently consisting of only 2 setiferous lobes. 

 Anterior maxillipeds comparatively small, resembling in structure those in Ectino- 

 soma. Posterior maxillipeds, however, more strongly built, with the middle joint 

 rather expanded. Natatory legs with the rami slender and narrow. Last pair 

 of legs built, on the whole, upon the same type as in Ectinosoma, 



