LAGIS KORENI. 55 



front. The tube is further chequered by a series of larger reticulations which cause it to 

 resemble crocodile leather. 



Mr. Watson mentions (in lit.) that Mr. Chadwick at the Port Erin Laboratory 

 observed the metamorphosis of the larval form into the post-larval, viz., the settling down 

 of the former on the bottom of a vessel ; it rotated rapidly for an hour and a half and then 

 was found to have secreted the membranous tube. 



The perseverance and ingenuity of Mr. Arnold Watson have lately enabled him to 

 observe the building of the sand-tube by a post-larval form in July. Thus one which had 

 cast its membranous tube endeavoured to manipulate minute sand-grains toward what 

 should have been the edge of the tube, and he subsequently was enabled to watch the 

 early post-larval form, which has only two buccal tentacles, by means of which minute 

 sand-particles (nfoo to loo mcn m s i ze ) are collected and passed to the mouth which 

 opens at their bases. What is required for food is swallowed, but those grains suitable 

 for building purposes are rolled over in the mouth and then deposited on the edge of the 

 tube (Plate CXIII, fig. 6). The annelid then advances slightly in its tube, and for four 

 or five seconds applies to that sand-grain the secretion of the cement-gland. The post- 

 larval membranous tube is thus the structure to which the first sand-grains are attached, 

 so that further use is made of this protection. 



Lagis Koreni is one of the most skilful artificers in the family of the Amphictenida3, 

 fashioning a tube like a slightly curved horn, composed of minute pebbles or large grains 

 of sand, carefully selected and dexterously fixed to each other by the usual secretion. 

 In placing the grains together in the tube there is no haphazard, but angle fits angle, as 

 in a skilfully built wall, and no excess of cement hides slovenly masonry. The tube is 

 perfectly round and dilates from the narrow end to the wider, which is often the lower 

 end in the sand, for the animal carries it thus, and its symmetry and workmanship are 

 faultless ; yet the architect is devoid of eyes, and depends on its exquisite sense of touch 

 and remarkable instinct. The tubes harmonise with their surroundings, 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. The tube is more 

 or less transparent in life, so that the position of the occupant can be determined from 

 the outside, the posterior end, however, being opaque from an accumulation of soft sand, 

 with a screw-like tunnel leading to the posterior end. Rarely a coarse tube is observed 

 at St. Andrews, the minute pebbles projecting from the surface like those of Pectinaria 

 graniilata, and to one a gelatinous capsule containing mucus ivas attached externally. 

 Much, therefore, depends on the nature of the ground inhabited by the specimen. 



Habits. — When weak the animal drops from its tube. A healthy example removed 

 from its tube and placed in sea-water constantly extends and contracts its body, the 

 tail moving more freely than the anterior end. It usually lives in the sand with the 

 wide end of the tube inferior, as first pointed out to me by the late Mr. David Robertson, 

 of Cumbrae (1889), who found the specimens between tide-marks, whereas at St. Andrews 

 they are only tossed on shore by storms. 



The great numbers of this species found in the stomachs of the cod and the haddock 

 off St. Andrews Bay show that in all probability they are swept in thousands from their 

 sites in the sand, and thus come in the way of fishes which feed on the bottom. Both 



