THE SCARCE POLYNOE. 391 



Eristalis tenax, that bee-like fly, that is so very 

 common in every garden in the latter part of the 

 summer, hovering motionless over the flowers for 

 several seconds, and then shooting suddenly away to 

 hover again in like manner. Its association here with 

 the Machilis and the Oniscus was a rather curious 

 circumstance. 



POLYNOE IMPAR. 



Sept. ^Ith. — In turning over stones at low water 

 on the outside of the harbour, I found an Annelide, 

 which appears to be the rare species described by Dr. 

 Johnston (Ann. N. H., Feb. 1839) by the name of 

 Polynoe impar. It is not more than half-an-inch in 

 length, and to the naked eye presents nothing con- 

 spicuous or worthy of special notice, but submitted 

 to microscopical examination it proves highly curious. 

 The kidney-shaped shields with which the back is 

 covered, and which are detached with slight violence 

 (though not quite so readily as those of P. cirrata), 

 are studded over with little transparent oval bodies, 

 set on short footstalks ; the intermediate antennee, the 

 tentacles, and the cirri of the feet are similarly fringed 

 with these little appendages, which resemble the glands 

 of certain plants, and have a most singular appear- 

 ance. If we remove the shields, we discover on each 

 side of the body a row of wart-like feet, from each of 

 which projects two bundles of spines of exquisite 

 structure. The bundles expanding on all sides re- 

 semble so many sheaves of wheat, or you may more 

 appropriately fancy you behold the armoury of some 

 belligerent sea-fairy, with stacks of arms enough to 



