NEMERTINE WITHIN TEST OF SEA=URCHIN. 



JOHN IRVING, M.D., 

 Scarborotigh, 



In connection with the marine exhibits shown at the annual 

 meeting of the Yorkshire Naturalists' Union, held at Scarborough, 

 it may be interesting to note that one of the Sea-Urchins, subse- 

 quently cut open, contained a worm of considerable length. 

 The Urchin, Echinus sphcera, five inches in diameter, healthy and 

 well-developed, showed no structural malformation internally, 

 notwithstanding the fact that its ccelomic fluid provided a 

 swimming bath for an interloper, measuring, when uncoiled, 

 between four and five yards long. The worm, unsegmented, 

 smooth, cylindrical, was but one-twelfth of an inch in diameter. 

 Through the transparent walls of its cuticle the milk-white 

 contents were well seen. Colour was entirely absent. Both 

 extremities tapered to a blunt point. Under low-power 

 microscopy, a central integumentary depression at the anterior 

 tip indicated the mouth, while a similar depression, eccentric, 

 at the posterior end, represented the anus. No armature of 

 any kind was observed. It was clearly a simple marine 

 nemertine. When, and how it found its way into the Urchin's 

 ccelom is a matter for conjecture. As an egg, or tiny embryo, 

 it may have succeeded in passing through the intestinal wall, 

 or through the porous structure of the test, into this cavity, and, 

 thus imprisoned, had no alternative but to make the best of the 

 situation. Doubtless the ccelomic fluid was nutritive enough 

 to support life, and permit growth. Albinism was manifestly 

 due to lack of light, as well as lack of coloured pabulum. 

 Evidence hardly warrants the idea of parasitism or commen- 

 salism. During the past three years I have examined many 

 Sea-Urchins, but this is the first in which I have discovered a 

 permanent unattached lodger. 



An excellent method of protecting the eggs of a colony of Terns and 

 Gulls has been adopted at Ravenglass. The eggs are marked with an 

 indelible pencil, and are thus spoiled for the cabinet. — British Birds. 



The Mining Magazine, edited by T. A. Rickard, is to appear monthly, 

 at one shilling, and the specimen before us is admirable. Anyone interested 

 in mining will find the publication most useful ; there is an astonishing 

 amount of matter, and the articles are well illustrated. 



Mr. F. W. Knocker deals with ' The Practical Improvement of Ethno- 

 graphical Collections in Provincial Museums ' in the Museums Journal for 

 November. This paper should be widely read, as it rarely happens that 

 the ethnographical objects in a museum are scientifically classified. 



Naturalist 



