XX THE VOYAGE OF H.M.S. CHALLENGER. 



On the basis of these researches Viguier proposed an amended classification of the 

 Asteroidea. He divided the class into two sub-classes, named " Astdries ambulacraires " 

 and " Asteries adambulacraires." The first characterised by the predominance of the 

 ambulacra! plates in the mouth-ring, the presence of pedunculate forficiform or forcipiform 

 pedicellarise, and the usually quadriserial arrangement of the ambulacral tube-feet ; the 

 second sub-class characterised by the predominance of the adambulacral plates in the 

 mouth-ring, by the presence of sessile, pincer-like, or valvulate pedicellarise, and by the 

 almost constant biserial arrangement of the ambulacral tube-feet. The first sub-class was 

 divided into three families, the " Asteriadae," Heliasteridse, and Brisingidaa. The second 

 sub-class was divided into seven families, the Echinasteridas, " Linckiadaj," Goniasteridae, 

 Asterinida?, Pterasterida?, Astropectinidse, and Archasteridse. 



The three families, Heliasterida?, Brisingidoe, and Archasterida? are additions to those 

 given in Perrier's list. Perrier, however, included the family Brisingidse in his remarks, 

 but did not include it in his synoptical table. The genera recognised by Perrier are 

 accepted by Viguier, Metrodira, Nepanthia, and Brisinga being the only additions on 

 his list. Viguier, however, defined the genera chiefly on the basis of his own investiga- 

 tions on the skeleton, the characters of the odontophore and the mouth-plates being used 

 by him as important factors in the classification. On these grounds several of the genera 

 are placed by Viguier in different families and associations from those to which they were 

 referred by Perrier. 



In 1879 Zittel 1 published a classification having special reference to fossil forms. He 

 divided the class Asteroidea into two orders — (1) the Ophiuridse, which was again divided 

 into two sub-orders, the Euryalese and the Ophiurese ; and (2) the Stelleridas, which was 

 subdivided into two sub-orders, the Encrinasteriad and the Asterias verse. The latter 

 group — which comprises all the recent forms — was simply divided into two unnamed 

 sections, characterised by the quadriserial and the biserial arrangement of the ambulacral 

 tube-feet. 



In 1884 Perrier 2 again discussed the question of classification, and pointed out that the 

 structure of the mouth determined by Viguier, and the character of the ambulacral furrow, 

 are morphologically correlated, the one dependent on the other, and that the modifications 

 in the form of the pedicellarise stand in no definite connection with the structure of the 

 ambulacral furrow and the mouth. From this he was led to discuss the relative taxo- 

 nomic values of the structure of the ambulacral furrow and mouth on the one hand, and 

 of the form of the pedicellariaa on the other. He decided in favour of the pedicel- 

 larise, on the ground that they are in his opinion aborted rudiments of ancestral organs 



1 llantlbuch der Pakeontologie, Miinchen, 1879, Band i. p. 437. 



2 Memoire sur les Etoiles de mer recueillies dans la mer des Antilles et le Golfe de Mexique durant les 

 expeditions de dragage faites sous la direction de M. Alexandre Agassiz (Nouv. Archives Mus. Hist, Nat., 

 2e Serie, t. vi. (1884) p. 134). 



