AT THE MICROSCOPE. 249 



small vessel containing the living specimen in sea-water, observing 

 to do so when the polypes are fully expanded. This intoxicates 

 them ; they die in their extruded condition, and can be removed 

 and mounted. The " BirdVhead " processes are remarkable 

 organs, which during life are continually moved upwards and 

 downwards with the regularity of a pendulum. Their structure 

 and nature have been carefully investigated by Prof. Busk. A 

 powerful abductor muscle closes the beak ; a small abductor opens 

 it. These are of striped, voluntary fibre. The centre of the 

 " head " is occupied by a body, which appears to be '' ganglionic," 

 and when the beak is widely opened a bunch of tactile hairs is 

 exposed. 



Ophiocoma neglecta is a highly interesting object. Note the 

 circlet of five didactyle pedicellaria, round the mouth-opening, and 

 the corona of them on the hard parts surrounding where the soft 

 inner structures commence ', also the curious claws on the under- 

 surface of the rays. W. B. Herapath, in the Qiuir. Jour. Micro. 

 ScL, 1865, pp. 175 — 184, may be consulted with advantage in 

 Pedicellaria; and G. Hodge, in Trans. Tyneside Naturalists'' Field 

 Club, has a valuable paper on the development of Ophiocoma 

 rostila, with a special view to these hooks, which he states to be 

 peculiar to the young Brittle Stars, and to be afterwards modified 

 into spines by a process which he fully describes, pp. 42 — 48, and 

 note on p. 64. Members residing near the seaside would do well 

 to confirm and extend these observations. 



Helix aspersa, Eggshell of. — A valuable contribution to our 

 knowledge, and quite original. To extend these remarks to the 

 eggs of other Helices and Gasteropods generally would be nice work 

 for our members. Has the action of acid been tried on these crys- 

 tals ? Some members seem to have very vague notions of the 

 formation of shells ; these should read carefully Carpenter's con- 

 tributions to knowledge on the subject in his Microscope and 

 Trans, of the Brit. Association ; also Bowerbank. Rainey, "On 

 the Formation of Shell and other Hard Structures," in Quarterly 

 Jour. Micro. Sci., republished in extenso by Churchill, must be 

 carefully studied. He was a splendid worker. 



Tracheae of Scolopendra has been coloured apparently by 

 magenta, to make it look pretty, some would say ; to show the 

 parts more distinctly, would be the verdict of others. This would 

 be more instructive if not pressed flat ; the specimen does not 

 profess to show the spiracle, the most interesting part of it in 

 reality. A portion of it is, however, there, and enabled me this 

 morning to confirm the correctness of the name by examining the 

 spiracle in the specimen of the " Great West Indian Scolopendra 



