NATURAL HISTORY SOCIETY OF GLASGOW. 17 



tective coloration in animals, and more especially in insects. He 

 described also how flowers had acquired their forms, colours, nectars, 

 and odours for the purpose of attracting insects, and of thus securing 

 the benefits of cross-fertilization. Also, on the other hand, how 

 many insects had their bodies, and particularly their mouth organs 

 and legs, modified in the most suitable manner for obtaining the 

 nectars and pollens offered by the plants, in exchange for the benefits 

 received by them from the visits of the insects. The paper was 

 illustrated by a series of coloured diagrams. 



III. — Note on Astrorhiza limicola, and on Amphidotus cordatus, 

 Penn. By Mr. David Robertson, F.L.S., F.G.S. 



There is an arenaceous Rhizopod, Astrorhiza limicola (Sandahl), 

 belonging to a class not admitted into our lists till lately. From 

 Siddall and Brady's Catalogue of British Recent Foraminifera, 1879, 

 it appears that this species is only known as British from the Dogger 

 Bank. For the credit of our Society it may be well to record its 

 frequent occurrence in the Frith of Clyde. I have dredged it round 

 Cumbrae on many occasions, and at one place abundantly; also 

 moderately often off St. Ninians on the west side of Bute. I 

 gave Dr. Carpenter specimens of it at the Meeting of the British 

 Association in 1876. 



The common Heart Urchin, Amphidotus cordatus, Penn., found so 

 commonly lying dead along our sandy shores, denuded of its spines, 

 has a feature in its habits that I do not know has been noticed 

 hitherto. They burrow from about 4 to 6 inches into the sand, and 

 when dug up and put into a vessel with sand covered with sea- water, 

 the animal is seen at once to commence to throw the sand to the 

 sides, by the under, or plastron spines. By the time that it gets 

 down into the sand, level with the under edges of the test, the spines 

 of the body get into motion, forming into 4 or 5, sometimes 6 or 

 7 ridges of spines, which stretch from back to front along the sides 

 of the test, progressing upwards in wave-like fashion, and following 

 each other in regular succession, till they reach the superior avenue 

 or summit. Each wave as it emerges from the sides of the animal, 

 brings up a roll of sand to the surface, which falls, outwards, 

 and this action is continued till the animal is completely covered, 



VOL. V. B 



