154 . Miscellaneous. 



Brachystoma angularis, Seeley ; Turbo Pictetianus, D'Orb. ; Pleuro- 

 toniaria regina, Pict. & lloux; ? P. Itieriaaa, Pict. & E.oux ; Pecten 

 RauUnianus, D'Orb. ; P. siibacutus^ D'Orb. ; and Lima Raidiniana, 

 D'Orb. The author described as new species Tarrilites nobilis, 

 Nautilus, sp. nov., Natica levistriata, Nerita nodulosa, and Lima 

 interlineata, and noted several corrections in the nomenclature 

 adopted in his former list. 



MISCELLANEOUS. 



On the first Bevelopraent of a Starfish. By "M. H. Eol. 



In a former note I endeavoured to show how the phenomena 

 described by M. 0. Hertwig in the sea-urchin may be compared 

 to those which have been observed in other animals. jS^everthe- 

 less the direct and continuous observation of these phenomena in 

 some creature allied to the urchin could alone furnish a positive 

 answer to these questions. With this object in view I made a fresh 

 study at Messina, during the months of December and January last, 

 of these earliest phenomena in Asterias gJaciuJis. 



The mature ovule possesses a large germinal vesicle and a very 

 distinct germinal spot. The vitellus is granular, destitute of vitel- 

 line membrane, but enveloped in a mucilaginous layer, which is 

 itself surrounded by a pavement epithelium. As soon as the ovule 

 gets into the sea-water this epithelium is detached ; the germinal 

 vesicle then shrivels, the distinctness of its contours is lost, and in 

 a manner it fuses in the vitellus. Its contents are never expelled, 

 as was supposed by M. E. van Beneden. The germinal spot also 

 loses its distinct outline, becomes paler, often changes its form, 

 gradually diminishes, and finally dissolves. All that can now be 

 seen in the vitellus are two light spots, one of which, very ill- 

 defined, still occupies the place where the germinal vesicle was, 

 while the other, which is of an ovoid form, approaches the surface. 

 The use of reagents reveals at this moment the presence of a double 

 protoplasmic star ; and I shall in future give to these united double 

 stars the name of amphiaster. 



This first amphiaster often presents in its neutral plane bodies of 

 irregular form, which I have reason to regard as relics of the mem- 

 brane of the germinal vesicle. The last remains of the germinal 

 spot are still visible at a certain distance from this amphiaster ; but 

 I shall not venture to assert that no fragment of the germinal spot 

 can enter into the composition of the amj^hiaster. I incline to think 

 that this first stellate figure is still not the one that gives origin to 

 the polar corpuscles, but that, on the contrary, it divides in the in- 

 terior of the vitellus, and that its peripheral aster alone gives origin 

 to the amphiaster which will be expelled. However this may be, 

 the vitellus soon presents only a superficial spot, which produces 



