CLASSIFICATION. 



CONTENTS. 



I. History of the Classification of the Asteroidea. 

 II. Seasons for Considering Previous Classifications Invalid. 

 III. A Classification of the Asteroidea based on Factors of Morphological Importance. 



I. History of the Classification of the Asteroidea. 



The earliest attempt to classify the Asteroidea was made by Linck 1 in 17.33, who 

 published the first monograph devoted to starfishes, entitled : De Stellis marinis liber 

 singularis. It is a work worthy of honour, and one which I hold in reverential estima- 

 tion. Linck divided the "Stellas marinas" into two sections, named " Stellas fssas" and 

 " Stellas integral " — the former characterised by the presence of an open channel or anibu- 

 lacral furrow along the actinal surface of each of the lobes or rays of the body, the latter by 

 the absence of these open channels. The Stellas fissas correspond to the Asteroidea of the 

 present nomenclature ; the Stellas integras comprise the Ophiuroidea and the Comatulse. 

 Linck divided the Stellas fissas, or section equivalent to the Asteroidea, into three classes, 

 which were based on the number of the rays ; the first class embraced forms with less 

 than five rays (all, by the way, abnormal or monstrous forms), the second forms with five 

 rays, and the third all those with more than five rays. The classes were subdivided into 

 genera, those included in the first and third being distinguished by the number of their 

 rays, jg In the second class, however, the genera were characterised by the general form. 

 This class contained seven genera, four of which are still maintained, viz., Pentagonaster, 

 Pentaceros, Astropecten, and Palmvpes. 



It will be seen from the above that the basis of Linck's classification is purely artificial, 

 the number of rays being the determinating factor. 



In 1766 Linne, 2 in the 12th edition of his Systema Naturse, grouped all the 

 Asteroidea, Ophiuroidea, and Comatulse known to him in one genus, Asterias, which he 



1 De Stellis marinis liber singularis, Lipsiae, 1733. 



2 Systema Nature?, Editio Duodeeima, Reformats, Holmia?, 1766. 



(ZOOL. CH-ALL. EXP. — part li. — 1888.) c 



