86 



we return more specially to this genus to examine the relation in which it stands to the 

 other known forms of the class Asteroidea. As is well known, the general view has hitherto 

 been that the genus Brisinga formed the type of an entirely separate group or order of 

 Asteroidea (Brisingastra Hackel) which as it were, formed the transition between the Asterida? 

 and the Ophiurida?. And to this conclusion we may really be easily led by considering the 

 animal's exterior habitus. But we shall now, after having become better acquainted with 

 the organisation of this remarkable form, be forced to come to an entirely different result. 

 Its relationship to the Ophiurida? is in reality very distant; while its conformity with the 

 proper star-fishes (Asterida) in all essential characteristic points is so great, that in spite 

 of its anomalous appearance, it must take its place in this order. In illustration of this 

 I will here briefly point out the characteristics whereby it connects itself with the Asterida? 

 and distinguishes itself from the Ophiurida?. 



1) The considerable and variable number of arms in the Brisinga has only its parallel in 

 certain Asterida?; while the number of arms in the Ophiurida 1 , in conformity with the 

 advanced centralisation, has mostly already become permanent as the typical number 

 for the Echinoderms 5. 



2) The ambulacral skeleton is in the Brisinga in its main features constructed exactly 

 according to the same type as in the proper star-fishes and differs essentially from 

 the ambulacral skeleton of the Ophiurida?. 



3) Also the cuticular skeleton shews a much greater conformity with the Asterida? than 

 with the Ophiurida?, and especially the connecting calcareous ribs over the basal sec- 

 tion of the arms are entirely foreign to the Ophiurida?; while it is easy to recognise 

 in them the analogon of the wide-meshed calcareous net found in the skin of many 

 Asterida?. 



4) Pedicellaries are never observed in Ophiurida?, while we find them in many Asterida? 

 of a very similar structure to those of the Brisinga. 



5) The structure of the madreporic body and its dorsal situation characterise the Bri- 

 singa as a genuine Asteride. 



6) Likewise the wide and deep ambulacral furrows, which are never found in the Ophiu- 

 rida?, where, on the contrary, the ventral side of the arms is covered with peculiar 

 cuticular plates (ventral plates). 



7) The water-feet of the Brisinga correspond in their strong development, and in their 

 whole structure, completely to those of the star-fishes ; and especially we do not know 

 any Ophiurida? in which they terminate in a clearly developed sucker. 



8) Neither do we find in the Ophiurida? any separate Ampulla? for the water-feet; while 

 these Ampulla? are in the Brisinga developed precisely in the same manner as in the 

 proper star-fishes. 



9) The perivisceral cavity is in the Ophiurida? confined to the disc only; while the arms 

 represent solid parts only containing a narrow canal for the reception of the radial 



