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



divided into three sections, named Integra, Stellatss, and Radiatw. The representative 

 of the first of these sections cannot now be recognised ; the second section is equivalent 

 to the Asteroid ea, and comprised nine species ; the third section embraced the Ophiuroidea 

 and Comatulse. 



Lamarck, 1 in 1816, divided the Asterias of Linne (which he regarded as a family 

 under the name of " Les Stellerides ") into four genera, which he named Comatula, 

 Euryale, Ophiura, and Asterias, the last being equivalent to the section " Stellatse " of 

 Linne, and to the Asteroidea of the present day. He divided the genus Asterias into two 

 sections: (i.) "Asteries scutellees," and (ii.) " Asteries rayonne'es," the former embracing 

 the species in which the length of the ray does not exceed that of the diameter of the disk, 

 and the latter those in which the length of the ray is greater than the diameter of the disk. 



In 1830 de Blainville 2 proposed to divide the Asteroidea (which he ranked as a family, 

 " Asteridea ") into five sections (" genres ou sous-genres "), which were characterised by 

 the general form, and by the number of the rays. The composition of the different 

 groups was more or less heterogeneous, and none of them have been maintained. 



In 1834 Nardo 3 grouped a number of species known to him into five genera, two of 

 which are maintained, viz., Aster ina and Linchia. 



In 1835 Agassiz 4 divided the Asterias of Lamarck (which he ranked as a family in 

 the order " Les Stellerides ") into nine genera, including fossil forms. Of the eight genera 

 in which recent forms were included, two are maintained in statu quo (Ophidiaster and 

 Cidcita), and the name of a third (Goniaster) is used in a restricted sense. The remaining 

 genera correspond to groups named by Linck or Nardo. 



This partition of genera was based on a number of structural characters, and was the 

 first approach towards a morphological classification of the group. 



In April 1840 Midler and Troschel 5 published a preliminary classification of the 

 Asteroidea, which they divided into three unnamed families, characterised by the presence 

 or absence of an anal aperture, and by the quadriserial or biserial arrangement of the arnbu- 

 lacral tube-feet. Fourteen genera were defined by means of structural characters, and 

 representative species were cited. Two years later this work was expanded into a com- 

 plete monograph on the group, entitled: System der Asteriden (Braunschweig, 1842), 

 which has formed the basis of all subsequent systematic work on the Asteroidea. In the 

 monograph the three families above indicated comprised eighteen genera, which included 

 140 species. 



1 Hist. Nat. Anim. s. vert., t. ii. p. 530, 1816. 



2 Diet. Sci. Nat., art. "Zoophyte," t. lx. p. 216, 1830; Manuel d'Actinologie ou de Zoophytologie, 1834, 

 p. 235. 



3 De Asteriis, Oken's Isis, 1834, Heft vii. p. 716. 



4 Prodrome d'une Monographic des Radiaires ou Echinodermes, Mem. Soc. Set. Nat. Neuchatel, t. i. 1835, 

 p. 190. 



5 Monatsber. d. k. preuss. Akad. d. Wins. Berlin, April 1840, p. 102. 



