12 Prof. W. C. M'liitosh on certain 



uses of tlic remarkable anterior bristle.?. He observes tliat 

 "on the three first post-occipital rings, gills, cutting-instru- 

 ments, and hooks are developed, each hook-bearing ridge 

 supporting at either end a brush of acutely cutting double- 

 edged setae which are fitted in the most perfect manner 



for dressing the materials wherewitli the tube is raised. By 

 them rough-hewn stones are polished, rugged surfaces worn 

 down, and angry pi-ojections from the interior of the tube 

 sm.oothed off." After some further remarks, he concludes by 

 predicating that " nothing in nature or art is comparable in 

 perfection of mechanism to these exquisite organs." While 

 I cannot go so far as Dr. Williams in his account of the 

 functions of tliese organs, there can be no question that the 

 bristles and hooks are amongst the most important structures 

 in all the varied movements executed by the annelids gene- 

 rally, and, further, that they are, individually, perhaps the 

 most reliable organs by which species can be discriminated. 



The most skilful architecture in the construction of tubes, 

 liowever, is exhibited by the family of the Amphictenidie, 

 one species of which is very abundant on the West Sands of 

 St, Andrews, viz. Lagis Koreni. This annelid fashions a 

 tube like a slightly curved horn, composed of minute {pebbles 

 or large grains of sand, carefully selected and admirably fixed 

 to eacii other by the usual secretion. In placing the grains 

 together in the tube there is no haphazard, but angle tits 

 angle, as in a skilfully built wall, and no excess of cement 

 hides slovenly masonry. The tube is perfectly round, and 

 tapers from the narrow lower end to the wider upper (for thus 

 it is inserted in the sand), and its symmetry and workman- 

 ship are faultless; yet the architect is devoid of eyes and 

 depends entirely on its exquisite sense of touch and remark- 

 able instinct. The tubes harmonize closely with their sur- 

 roundings, the wall being formed of similar proportions of 

 pale sand-grains of yellow, brown, and black, probably because 

 in such a selection the average colours are fairly represented. 



With a tube more distinctly curved and of a more slender 

 and graceful outline, Amphictene aun'coma is one of the best 

 known as well as one of the most interesting of the series 

 (fig. 4). In this the grains of sand are finer than in Lm/i's, 

 especially in small s|)ecimens *, but are placed together with 

 equal skill and care, so that the tube is perfectly rounded and 

 apparently smooth, for the slight elevations caused by the 

 sand-grains are only visible under a lens (lig. 5). Like the 



* It is probablo that the tubes in the <rrit\viiig niiiiiial are shed at 

 intervals, and new ones formed. Thus the tube of the adult dilVers in 

 regard to the size of the grains of sand. 



