DE. P. H. CAUPENTEE ON SOME AECXIC COilATFL^. 



61 



Typical Arms. 



3 3 3333333333333 3 2 3, or 3^', 2, 3, 



4544445654354442 5, 



34344555334343 3, 



233234 3 523542 4, 



2223 2223222 32 325342 3. 



From these data it may, I think, be fairly concluded that the 

 typical number of joints in the syzygial intervals of Antedon 

 prolixa is 3, as in A. Eschricliti •, while in A. tenella there are 

 not more than 2, as in the allied species A. exigua. This cha- 

 racter, taken in connection with those of the cirri, radials, and 

 arm-joints, serves to distinguish the two species very clearly ; and 

 I see no reason for uniting them, as Fischer has done. 



He supports his views by remarking* : — " Solltea noch irgend 

 welche Zweifel entstehen, so werden dieselben wiederlegt durch 

 die Thatsache, dass ich gleichzeitig mit den bereits beschriebenen 

 Exemplaren zwei Pentacrinus-'^t3i6.\Qn. auf einer BJiynconella 

 aufsitzend fand, die vollkommen mit den Beschreibungen Uberein- 

 stimmen, die Sars in seinen 'Memoires des Crino'ides vivants' gibt, 

 und auf Taf. v. und vi. abbildet. Die von Jan Mayen mitgebrachten 

 Exemplare entsprechen dem Entwicklungsstadium, wie es Sars 

 auf Taf. V. fig. 9 entwirft." An enlarged view of the head of this 

 individual is given by Sars in fig. 11 of the same plate, which I 

 have copied on Plate II. fig. 8, in order to compare it with the 

 Jan Mayen larva, which Dr. von Marenzeller has kindly sent me 

 for examination (fig. 1). They are, as Fischer remarks, at the 



* Log. cit. p. 30. 



