404 Scientific Intelligence — Zoology. 



philosophers to believe that these fragile creatures could possibly 

 exist at the depth of nearly two thousand fathoms below the surface ; 

 yet, as we know they can bear the pressure of one thousand fathoms, 

 why may they not of two ? We also know that several of the same 

 species of creatures inhabit the Arctic, that we have fished up from 

 great depths in the Antarctic Seas. The only way they could have 

 got from the one pole to the other, must have been through the 

 tropics ; but the temperature of the sea in those regions is such that 

 they could not exist in it, unless at a depth of nearly two thousand 

 fathoms. At that depth they might pass from the Arctic to the 

 Antarctic Ocean without a variation of five degrees of temperature ; 

 whilst any land animal, at the most favourable season, must experi- 

 ence a difference of fifty degrees, and, if in the winter, no less than 

 one hundred and fifty degrees of Fahrenheit's thermometer — a suf- 

 ficient reason why there are are neither quadrupeds, nor birds, nor 

 land insects, common to both regions. — Sir James C. Boss's Voyage 

 to the Southern Seas, vol. i. p. 207- 



14. At a meeting of the Academy of Berlin on 29th October, 

 a memoir on the larva state and metamorphoses of the Ophiurse 

 and Echini was communicated by M. Miiller. 



In 1845 M. Miiller made us acquainted with some animal forms 

 observed at the island of Heligoland ; these animals he has made 

 the subject of additional researches. The Vexillaria flabeUum he 

 has ascertained to be the larva of an Ascidia, probably of Amau- 

 roncium proliferum, Edw. But an object of greater interest, is the 

 development and metamorphoses of an animal which, on account of 

 its form and equivocal skeleton, has been named Pluteus paradoxus. 

 From this an ophiura was produced ; it thence follows that the Plu- 

 teus paradoxus is an ophiura. The earliest observations on the de- 

 velopment of an Echinoderm are those made by M. Sars on the 

 Echinaster sanguinoleutus (E. Sarsii, Mull., Trosch.) and Astera- 

 canthion Mulleri, Sars. This naturalist, whose discoveries have 

 added many important facts to our knowledge of the transformation 

 of the lower animals during their development, has likewise observed 

 that the young sea-stars had no resemblance to their ulterior form. 

 But he has given very few details respecting the internal structure 

 of these larvae, which doubtless proves that they are completely 

 opaque. The larva of the Echinoderms, which form the subject of 

 M. Muller's memoir, are so translucent that they admit of a micro- 

 scopic analysis even to a size 250 times their diameter. This na- 

 turalist has published in Wiegman's Archives (1846, p. 101, tab. 

 vi., figs. 1 and 2,) a description and figure of Pluteus paradoxus, be- 

 fore giving us an account of a sea-star. He does not therefore re- 

 vert to the subject, but merely remarks that this larva has no con- 

 nection with that described by M. Sars, unless that the animal 

 develops itself in one direction, and that it is bilateral ; but in other 

 respects, it presents a structure so peculiar and abnormal that it 



