THE NAUTILUS. 



VOL. XXVII. NOVEMBER, 1913. No. 7 



NOTES ON THKACIA CONRADI. 



BY EDWARD S. MORSE. 



For years I have hunted m vain for a living specimen of Thracia 

 conradi. This year my friend John M. Gould has collected speci- 

 mens alive in Portland associated with Solenomya borealis, and the 

 expanded animal is so interesting that I am induced to publish these 

 observations ahead of my other work on the subject. After storms 

 I have repeatedly found the broken shells, often with the adductor 

 muscles still adhering, but never a perfect specimen. The gulls 

 immediately recognize the conspicuous white object on the beach 

 and break the thin and fragile shell, devouring the fat morsel within. 

 The gulls alone are not entirely responsible for the fractured shells. 

 A live specimen was sent to me from Portland carefully packed in 

 seaweed. It arrived with the umbonal region of one valve broken 

 and the fractured portion standing at right angles to the vertical 

 axis. Jeffreys reports the same feature in the British species of 

 Thracia. He says : " The power of tension continually exercised by 

 the strong and elastic cartilage exceeds that of the shell, and the 

 latter being the weaker body gives away and is split in the conflict. 

 Only one species ( T. distorta), which is comparatively more solid 

 than the others, resists the strain and remains uninjured." 



For many years I have collected living specimens of New England 

 mollusca for the purpose of drawing the expanded parts of the 

 animal, and nearly all the larger, and many of the smaller species, 

 have been drawn. I have been led to do this in the belief that the 



