212 ON COPEPODA AND OTHER CRUSTACEA 



southern habitats have been described by Giesbrecht and 

 other writers. I cannot, however, identify our Northumbrian 

 specimen with any of these : it is here figured as fully as 

 possible. An interesting fact connected with this collection 

 is that two such extremely distinct and easily recognized 

 creatures — both of them of distinctly southern distribution — 

 should have occurred in this dredging, but have never before 

 been found in British waters. It seems probable that both 

 species — which are really pelagic in habit — were captured 

 not at the bottom, but on the passage of the dredge 

 upward to the surface. And it is not unreasonable to 

 suspect that there may have been a previous prevalence of 

 southerly winds or currents which might have brought into 

 our latitude these certainly unusual visitors. It should be 

 noted here also that one of the new species of Thalestris 

 {T. robusta) was taken, not on the dredging excursion here 

 recorded, but on the shore at Cullercoats. 



Genus MICROSETEBlLA, Brady and Robertson. 



Body cylindrical, tapering towards each extremity (Plate 

 III., fig. i), head coalescent with the first thoracic segment, 

 cephalothorax composed of four, abdomen of five segments, 

 caudal segments short and bearing long terminal setae, rostrum 

 short, falciform. Antennules of moderate length (fig. 2) five- 

 jointed, bearing on the third joint a stout sensory appendage. 

 First four pairs of feet (fig. 3) having both branches three- 

 jointed, the outer branch shorter than the inner, fifth pair 

 (fig. 4) foliaceous. (The antennule of the male forms a strong 

 prehensile organ, and the feet of the fifth pair are much 

 smaller than those of the female. — Giesbrecht). 



The genus Microsetdla was established by myself in concert 

 with my friend the late Dr. Robertson in 1873, but I after- 

 wards * withdrew the generic name, uniting the genus with 

 the previously described Ectmosoma from which the com- 

 paratively small differences seemed to me scarcely sufficient 



* See Mouoij'raph of the Britisli Free aud Semiparasitic Copepoila, vol, ii., p. 13. 



