326 Miscellaneous. 



of the nervous system are far from presenting the same analogy. 

 We find in it, in fact, two lateral nervous trunks such as exist in 

 many groups of Tubicolar Annelids, and not a median chain like 

 that of the Polygordians. The segmental organs also present con- 

 siderable differences. 



It would he very desirable to determine by an embryogenic in- 

 vestigation the exact degree of relationship of the Polygordians 

 and (Jpheliidas, which comparative anatomy leads us to suppose is 

 very close. The embryo of Polygordius is an embryo of a primitive 

 Annelid, a typical Trochosphcera. We have no information as to 

 the cmbryogeny of Polyophthalmus. The supposed embryos of 

 Ophelia, described and figured in a recent memoir, are unfortu- 

 nately only embryos of Arenicola piscatorum. — Comptes JRendus, 

 August 9, 1880, p. 341. 



The Starfishes of the deeper Parts of the Gulf of Mexico. 

 By M. E. Perkier. 



For two consecutive years Mr. Alexander Agassiz, on board the 

 ' Blake,' has performed a series of dredgings in the deep parts of 

 the Gulf of Mexico. He has obtained the most brilliant results, 

 and has done me the honour to confide to me the task of studying 

 and describing the numerous starfishes that he has collected, forming 

 a collection of more than 300 specimens. I beg leave to submit to 

 the Academy, in a few words, a summary of my researches. 



Luidice, Archasteres, and Goniasterida) form the basis of this im- 

 portant fauna ; but we also find iu it Linckice, Echinasteres, Solasteres, 

 and several Pterastcres ; and the great division of the Asteriadae is 

 represented by some exceedingly remarkable forms, to which I shall 

 devote this first notice. In 1874 Wyville Thomson described, under 

 the name of Zoroaster fid gens, a starfish of the section Asteriadse, 

 which was met with only once in the Atlantic by the ' Challenger,' at 

 a depth of 707 fathoms. The genus Zoroaster, which is distinguished 

 in the family to which it belongs by the thickness and regularity 

 of the skeleton of the starfishes included in it, is represented in the 

 collection of Mr. Alexander Agassiz by two new species, to which 

 I propose to give the names of Zoroaster Sigsbeei and Z. Ackleyi, in 

 honour of the captain of the ship and his lieutenant. Z. tiigsbeei 

 is at once distinguished by the considerable projection made by the 

 enormous ossicles of its disk, which is thus rendered clearly distinct 

 from the arms and comparatively voluminous. The arms, which 

 are nearly rigid, are conical ; and their skeleton consists of nine 

 regular series of square ossicles. In Z. Ackleyi the ossicles of the 

 disk are not salient, the disk is continuous with the arms, which 

 are about twelve times as long as its radius, so that the animal has 

 the physiognomy of a Chcetaster. These arms are much more mobile 

 than those of the other species, and are formed of seventeen rows of 

 rather small ossicles. In the two species which I have before me 

 the plates of the ventral region of the arms are covered with small 

 flattened spines placed close together and intermixed with larger 

 spines, so as to recall to mind the covering of the ventral surface of 

 the Luidiaz ; the adambulacral plates even bear, as in the latter, a 

 comb of compressed spines, the direction of which is perpendicular 

 to that of the ambulacral groove, and the innermost of which is 



